Long ago, I developed a rather complex headcanon for the Changelings. I am now finally typing it up here.
Take note. This was made long before the comic backstory was made for them. And honestly, that backstory for them was quite stupid. No one recognized the changelings except for Cadance due to her having been imprisoned by them for so long, so the story that was used for their backstory didn't make sense... regardless of the funny jokes involved in it. And as such, this headcanon does not take that into account.
However, this headcanon will be used in my upcoming fic(s). And, any whom read this are free to use my concepts however they see fit, as long as credit is given.
For these details, I shall separate them into parts, and give my reasoning for my concepts at the end of each section.
For the hive mind, the Changelings are able to contact one another psionically with their minds, as long as they're within range of those they're communicating with. This range is usually fairly far, so as to keep a hive in order and under command. It also has additional effects, which will be described when getting to queens.
Reason for Hive Mind's Existence:
When Chrysalis called for her armies, she did so through the force field. The force field is meant to block magic and other attacks, yet she called on them and the message got through. Not only that, but she didn't use her magic to do so since her horn didn't glow. Yet, she contacted them through solid walls. A psionic hive mind explains this event well.
Reinforcement of Limited Range:
During Slice of Life, the fact that there was a Changeling willingly there out in the open, as opposed to Chrysalis' totalitarian view of thing, is a good indicator that the hive mind likely can't reach it and give it orders from wherever Chrysalis currently is. That, or he's from a separate hive than Chrysalis'. One of the two likely being the reason, if not both.
For Changelings, their transformations are completely physical, or at least it is for those old enough to do so. Those that are too young instead utilize illusions.
To explain these, there's first the explanation of why they can do so so easily, beyond just their bodies being adapted to have an affinity with transformation magics.
For their transformations, the reason for them being able to do so so easily is because they don't control the magic fully. Instead, they link their magic to the magical leylines running through their planet, which acts like a sort of semi-sapient database. This database provides the full details of the form they're transforming into, even internally. By linking their magic to this database, even the dumbest of drones can transform with complete physical accuracy.
As for those too young to perform transformations, that is because transformation magic is dangerous, and they are only allowed to do so after they've confirmed being able to get complete physical illusions through much the same method. Illusions don't actively harm the body when used as a disguise, and thus are used as a testing phase till they've learned to accurately link to the leylines of their world.
Thankfully, accessing the leylines is fairly easy. These magical leylines I'm referring to traverse the entirety of their world, BUT, it is true that it's easier to access in some locations as opposed to others due to the fact that how thick these energy/data flows are vary from location to location. It's usually far easier to link to when the leylines are thick, since they're all interconnected and the thicker energies are easier to detect than the thinner leylines found in some locations.
Despite transformation via the leylines having been made a lot easier due to their transformation affinities, they unknowingly drain their own energies to use such fairly quickly, making them physically weaker in the process. Due to this, only princesses and queens don't suffer as badly from transformation overuse.
This distinction is because the changelings transform so much that they lack any specific organ to generate their own mana, thus needing to drain others for it. However, due to ascension, princesses and queens have compressed enough mana within their bodies that they've ascended on a cellular level, turning every cell into a mini-mana generator. Though small in efficiency, the number of their cells working together to generate mana helps make princesses and queens far more powerful, their cells working much like how their hive works: together in mass numbers. This also makes the mana cost of transforming less of an issue for them.
Even though these transformations should make them extremely dangerous in combat, what with likely being able to turn their own bodies into weapons or even granting enhanced physical traits with enough energy for the more drastic changes, they do not seem as dangerous as what their transformative abilities should provide. In fact, they seem much weaker than ponies despite their advantages.
Reasons for the Easy Total Transformations:
There are many reasons for this one. For one, Twilight has proven able to easily cast transformation spells quite often, what with both the Breezies ep and the ep where she turned a frog into an orange. The idea of a semi-sentient leyline as the reason would also explain how the frog survived that fiasco.
Counterargument to the Contradicting Age Spells:
We know that Twilight couldn't do the age transformation spell because of its difficulties. But, based on the crying involved from that, it wasn't just a physical transformation, but a mental transformation as well. And as proven by Chrysalis having to use such magics multiple times to have an effect on Shining Armor, mental change spells are noticably harder than physical change spells.
Reasons for Not Transforming Their Bodies Into Weapons:
Simply put, the majority of Changelings are dumb, though not by necessity, as I'll explain when getting to the tiers. This means most would not think of making advantage of such a transformation. And even if they did make use of such, most would lack the training to utilize such an advantage properly. So, it's not that they can't, but rather, it's because their way of life has caused most to lack the creativity to think up such a task.
Reasons for Being Weak in Combat:
The simple reason for the changelings being so weak, as proven when fighting Twilight in that first large squad, is because of them using up their magic too much for transforming. Their numbers alone should have been enough regardless of this, but the difference of strength was too much. As for how this made them too weak, I'm in debate on two reasons for this, though I'm leaning towards the latter of the two:
Potential Reason #1:
Using up their transforming magic too much drains them without noticing at a quick rate, causing overall weakness, like how dehydration effects a human faster than they realize till it's too late.
Potential Reason #2:
Due to channelling their magic towards efficiently transforming as much as possible, this subconsciously prevents them from channelling their magic into their bodies to enhance their speed and strength. As proven in the show, ponies are far stronger and faster than should be physically possible, and far more durable as well, as proven when Rainbow Dash only walked away dizzy after flying head first into that massive tower of stones Spike stacked when he was repaying his life debt to AJ. And without that natural magic enhancement to their bodies, they can't take nor deal nearly as much of a hit to ponies as ponies can deal to them. Though Changelings are completely unaware of these weaknesses they have, let alone what the causes for them are.
As has been shown, Changelings are pony insectoids, and they have a queen. They follow this queen without question. They're kept mostly dumb, so as to keep them in line and following orders. Only a small few Changelings end up smart, some of which are given armor as recognition of this and given the job of giving orders, in turn reducing the toll on the queen in terms of giving orders.
Reasons for Stupidity:
They've been shown to be stupid due to them ramming the force field with any part of their body that they could. Only a select few were willing to just use their hooves, which are more durable. Some were even dumb enough to ram in eye first.
Reasons for Following Orders Without Question:
Beyond just the proof of them being stupid, there's also the fact that they instantly followed orders without question, the dumb ones included. As such, the only way to be so quick to follow orders is if they're trained to do so, as if it's expected of them, and they are likely used to following orders from their queen for their hive.
Reasons for Select Few Smart Changelings:
Not only were there some Changelings that attacked the force field more precisely, like through hooves while watching what they were doing, but also, there were Changelings running around during the invasion that had armor being worn. This is a distinction of superiority, and said changelings were in front of a group of changelings that were following behind them, as if following a leader. This gives credit not only of smarter changelings having the potential to be trained into leaders, but also gives credit to the thought that they're given such positions to make ordering around the hive easier for the Queen by allowing her to not have to focus on the groups these armored changelings are ordering around.
Personally Theorized Details on Culture:
With their lives being so utilitarian, they're trained from youth to obey and follow orders for the good of the hive, even at the cost of their own lives or personal injury, as proven with the dumbness previously mentioned.
With such a utilitarian approach, they likely separate the feed they gain from emotions based upon merit, having recorded the details of such via the hive mind. And considering the glow of goo pods in both the show and first comics, it stands to reason that they can channel their stolen emotional energies through the goo, so as to provide a measure for measuring the 'food by merit'.
It also stands to reason that those with higher food gains from the merit of their work would in turn be more smart. Kind of a chicken or the egg paradox: More intelligence means having the intellect to better prove their merit, and having more food from merit increases the likelihood of their minds becoming more healthy. In the end, the main issue towards this is simply getting the starting point going, since Changeling Drones live most of their lives doing nothing more than following routine, orders, and the basic training done during their early years. Once something has sparked the desire to do more than orders, though, and it is noticed... then that Changeling is taken under the wing of whomever is in charge of what could have sparked that thought, so that that spark of thought can be nurtured in a way that is convenient to the hive as a whole. Curious about the outside? Tracker. Deceived someone? Infiltrator. Created something? Builder. And etc. etc., with each semi-rare Changeling to show signs of sapience being trained to make that sapience useful for the hive.
Obey, work for the hive... that's all they know. So it's not so much that Changelings are stupid. It's just that they live in such a culture where thinking for themselves is not encouraged actively. And only those that prove themselves are trained to think beyond orders. In fact, I wouldn't doubt it if they're not even named till they do prove themselves. Living the life of a pawn, a pawn happy to live such a life because they don't know of any alternative. Sure, there are the lives of others, but those are their species, and Changelings are their own species. What works for one does not for sure work for others.
Not only that, but having such a 'blank slate' actually makes it easy to put false personas upon them. Less individual personality to conflict with the false persona they are granted.
Then, there's the issue of why peace isn't considered. By being able to shapeshift in any way as long as the energy is available, there's a decent reason to believe that they are the superior species, in part due to not realizing the downside that comes with the transformation. Despite this, they stay in hiding due to their numbers not being on par with the other nations that they can feed upon.
Not only that, but due to 'preying' on the other species, they don't consider peace with prey as an option, regardless of how much their kind may be starving due to having to feed off them in stealth.
And considering what was shown during the invasion, it's quite unlikely there's many a changeling skilled enough to maintain a false identity for too long of a time without risking being unveiled. So, they likely keep to fast love and/or lust, and those that actually manage to get actual love can feed their hive a lot more than just lesser emotions to feed upon.
It's been shown that Changelings feed on love. But, love alone couldn't feed an entire hive, even if said love is love enhanced mana, utilizing emotions as a psionic channel to feed upon mana. So, it's more likely that they feed upon positive emotions as a whole, with love being the most potent.
It's also likely they can feed on negative emotions, but if they try to feed on love, that means that negative emotions likely aren't as good for them. In a way, negative emotions could even be poisonous for them. It could be considered like food poisoning. The food ate would still provide nutrients, but would those nutrients be worth the temporary poison that comes with it? In some cases, it would, while in other cases, it wouldn't. Depends on the severity of the poison, or in this case, the severity of the negative emotions.
Regardless of the type, however, they had to have fed on the emotions in a subtle way not directly using their magics, since if they did so through a more visible way, knowledge of the Changelings would be well known long before the time they were revealed.
However, it's unlikely that they digest the emotions immediately. They likely only store them till they can bring them back to the hive, due to their utilitarian natures. And then, they digest the 'food' that they are given.
But it's unlikely that they only feed upon emotions. Their teeth prove that much. A combination of flat and fanged teeth. If they only had teeth for attacking, it'd only be fangs. But, they have both, so they likely feed upon physical food and emotional food, with the emotional food replenishing their mana so that they don't suffer the adverse physical effects caused from mana exhaustion.
Captive Pony Details:
As shown in the show, Changelings are able to capture their prey in goo made pods. Also, as shown in the first comics, they are put in stasis in those pods, with it widely accepted by fans that their stasis like state is one that influences love like emotions through their dreams for them to feed upon, while the pod continues to nourish the captive for a prolonged food source.
However, no matter how much this prolongs the food source, it'd still have limits. Chances are, they are careful to avoid ruining a food source, alternating between pods to give some pods enough time to recover.
But, even with this, a pony suffering this for so long will likely suffer side effects, their mind eventually breaking under the forced false reality the pod puts their dream state into.
With this in mind, a pony would likely eventually become useless to them if fed on too thoroughly for too long.
Recycling Broken Ponies:
Due to their utilitarian mindscape, I theorize they developed a way to 'recycle' the ponies whom have been fed on enough for their minds to break, unable to think enough to form emotions. With their minds broken, they no longer have defenses against mental magic. Add in physical transformation magic to the mix, and a used up pony could be completely remade into a new drone for the hive once their mind is thoroughly broken down to the point where the mind magics can have a clean slate to work with. Without the past mind status to oppose the magics, they'd no longer be temporary, and thus a full transformation into a Changeling is possible if placed under the magics long enough to be permanent.
With the pods acting as enchanted structures, they can last longer than a focused mind could, and thus could make such a prolonged exposure possible if created with the purpose of conversion in mind. Though, that likely means different pods would be needed to be made for the different jobs of conversion and providing a food source. Possibly an additional pod type for switching them into for recovery till they're too used up for said recovery pods to restore them to feeding status.
Regardless of the method however, this recycling method makes use of the dead victim's body. This has the added benefit of preventing the dumping of their dead body from attracting attention to their hive's hiding place.
Thankfully, it's fairly rare to need to do this, since the upkeep of victims is fairly well managed. Plus, drones tend to be gained in more numbers via the natural methods. Admittedly, drones made from converting often show what they're better in faster than naturally born drones, but not enough to where it compensates for the easier method of just giving birth to new drones.
Mind Controlled Ponies:
It's quite unlikely that they turn ponies into living puppets. As proven with Chrysalis, it takes a very long time and several attempts to break a mind into a slave, and even then, it's temporary enough to be able to break. Not only that, but it's obvious too, with the green eyes and whatnot. As such, enslaving ponies wouldn't have much long term use. They couldn't even be used as spies due to the green eyes deal.
Short term use is another matter if the pony is powerful and can be subdued without the victim suspecting the used mind control spells, but since the spell is so obvious and easily suspected, that means that such a method is rarely used.
Instead, the more useful short term use for the mind control spells would likely be for gaining information, enslaving their minds long enough to steal information from the target that could be useful to the hive, with the victim never being aware of what knowledge was given to the changeling they were obeying.
Changelings rarely stay around for long when it comes to love unless they're very experienced with infiltration. The longer a changeling stays, the easier it is to be caught in their deceit.
As such, Changelings usually go two main routes when going for the larger scale emotional meals, focusing instead on a quick meal instead of a long term replacement in order to get food back to their hive more quickly.
Replacing An Already Established Love:
This one is hard to pull off, but very rewarding. This involves kidnapping someone already in love with another, and then replacing them, much like what Chrysalis did. Provides the most potent of emotions, but such a feast tends to not last long due to having to keep up a prolonged act, which very few Changelings manage to succeed in doing, at least in the long term.
Going for the Less Potent Emotion of Lust:
Most early Changeling infiltrators go for the lust route. With this, they can get a quick yet decently heavy meal. Often, they take a highly attractive female form, since females often can more easily attract either gender with just looks alone.
Due to this choice of becoming female to attract lust, most Changelings that leave the hive for their jobs tend to identify themselves as female when choosing a gender. There are, of course, exceptions to the rule, but they're fairly rare.
Regardless of the gender chosen, this lust hunting process, though not as potent as love, provides a very easy and quick snack for many early starting Infiltrators. And by using it, they learn things the 'strange ponies' like, helping them when they decide to pursue the more potent love emotions.
As mentioned earlier, Changelings, due to all the transformations, are asexual. But, they can CHOOSE gender to turn into, should they wish.
Most Changelings that remain in the hive and don't adventure outside of it tend to never choose a gender, unless influenced from Changelings whom have come from outside of the hive.
Most of the changelings that DO change genders tend to pick female, due to the previously mentioned fact that it's easier for female to attract both genders. And since most Changelings that go out tend to choose female for their sense of self-identity, most Changelings in the hive that choose on an identity tend to choose female as well.
However, they choose this not due to understanding the advantages and disadvantages of being female. Instead, they choose this because they see that most Changelings that understand what gender even means tend to prefer female forms.
Basically, those in the hive that don't understand the importance of gender tend to choose female cause most everyling chooses such. They think that it's only logical that there must be some reason for preferring that gender, and thus choose such for themselves, without understanding the reason why others chose such.
Despite all this though, most Changelings in the hive that don't venture outside tend to remain asexual, due to simply not understanding the reason for doing so. Of course, they can change their minds later.
The Use of Sex to Changelings:
Since Changelings excel in transformation magics and being adapted to them, it is my opinion that, physically speaking, Changelings are overall asexual. Their transformation magics allow them to choose their gender at will. Admittedly, when they've gained enough self identity, they're likely to choose a gender to go with it.
However, though they can choose a gender identity, they tend to not do sex as Changelings, cause to them, sex is just a method of eliciting high emotions. They never really had reason to learn where pony children came from, nor do they have any reason to connect the act of sex with it.
That's not to say they're not smart enough to learn this. Rather, they're so utilitarian that they have no reason to think of what other ponies do that isn't a direct consequence for them.
Not only do they have no need to look into the details of what sex causes, but they also in turn have no idea what causes the occasional 'morning sickness' some Changelings have after using sex to feed, which happens fairly often. But, they do not look further into it, cause the 'morning sickness' for them often leaves whenever they transform again. Due to this, they never had reason to look further into the matter: neither its cause or what consequences it could mean to them.
For the changelings, whom feed off of mana through emotions, their reproduction is... unusual. Although they're unaware of how unusual it is, since one of their potential methods to reproduce is unknown to them. This method is unknown because their constant transformations prevents an embryo from developing.
For this first method, it involves the fact that they're asexual. This means that any of them have the potential to give birth, to eggs primarily due to their insect like qualities. HOWEVER, 'possible' and 'plausible' are two different things.
As mentioned, the energy the Changelings have depends on merit. It takes a decent chunk of energy to produce an egg. And due to the bit about merit, it'd nearly kill a drone to use their energy to produce even a single egg. The higher tier the changeling though, the more eggs they can produce, and the less straining it is to do so.
Due to the energy strain though, it is very rare for a non-royal level changeling to produce eggs. Possible, but rare. This is made all the more rare since they have to direct their energy into producing such, and having a lower tier changeling need to produce more changelings is an incredibly unlikely scenario.
The second method is basically sex. It is possible, due to the total transformations, for Changelings to have sex and mate that way with any species they can turn into. But, the Changelings themselves are unaware of this, because they practically never stay in a form long enough to even realize that they've become pregnant, and the transformation they undergo essentially destroys the embryo forming in them without them even being aware they have done so.
Although, they do know that taking a moment alone before sex to turn into the same mare in heat tends to bring out even more lust for some reason, despite the complications that come with. Mainly just knowing this from rumors and the like from other Changelings that have done so.
What's ironic, though, is the fact that if they did go through with having a child through sex, the resulting changeling would be quite noticably stronger than normal due to the constant care and desire to protect directed to the developing child. It'd be like feeding it love all through the formation phases of the egg. Actual love, instead of the minimal run-off needed to feed and hatch the egg.
If a Changeling that chose male as their gender identity was to ascend fully, to King status, and mate with another hive's Queen... the result would be one incredibly powerful Changeling child. But, each of those three components for such are rare. To have all three would be incredibly unlikely. Not impossible though. Just rare enough to be considered a legend or myth.
Hatchlings, as newly born changelings, don't know much, and must be taught. However, Changeling classes are not meant for fun. It's hard and gruelling, teaching the basics of transformations, flight, basic goo usage, following orders through the hive mind, using the hive mind to act as a swarm, etc. None of the advanced knowledge till a drone has gotten through a task.
Hatchling classes are harsh. Unless damaging to the hive, they are not punished for mistakes, but neither are they praised. They only get praised for following orders, and then ordered to do so better if they haven't already done so before. Strict, but fair.
Even Hatchlings that haven't learned to speak are treated strictly, since those that train them can force enough of a hive mind connection to detect the truth from their minds, as well as to ensure that their minds know what is right and wrong to do, though it arguably takes a lot more energy to use the hive mind to get this point across rather than words.
Once a Hatchling has proved adequate enough in all the basics, and their proficiencies recorded, the Hatchling, its recorded number(no name for the to-be drone), and its statistics are sent in to the generals, a.k.a. Elites, to peruse and decide where best to distribute them, often alternating the unnamed drones between many sections of the hive based not on skill but on the need of numbers of drones, since said drones have yet to prove to be especially good at any specific task.
Overall, Hatchling training isn't about finding out what Changelings are special in. It's designated to grind into their minds the desire to follow all orders to completion, regardless of distractions.
That's not to say they can't be distracted. But the focus here is for them to follow orders regardless of any personal thoughts they may or may not have. Orders to Changelings are everything, or at least it is to Changelings whom are still within range of the Hive Mind they've been raised in.
When a Drone has finished basic training, they are then sent to a general gathering of Elites together with their fellow 'graduates' along with the details of their proficiencies in the basics and their number designation. After presenting themselves to the elites, they are then distributed to a select grouping of various tasks where they can best help the hive. Due to them just finishing basic training however, it is rare for such class designations to be made with clear decisions. As such, most drones are randomly sent from job to job in the hive till a place can be found where they excel.
More often then not, most drones are unable to find such a niche, due to the fact that the basic training they've been put through focused so much on them neglecting thinking anything other than following orders and completing them. However, those that do find such a niche are then brought to focus.
Drones brought to the focus of the Elites and Princesses are examined, discovering what may have allowed them to show individuality along with what that individuality was directed towards. From there, it's decided what best way to make USE of those qualities for the betterment of the hive. And once that has been decided, they are then sent to the princesses and elites in charge of the class those qualities are best for, putting said drone into an In-Training session, one specialized for what their individuality seemed attuned to.
During the In-Training phase, a Changeling is put under the wings of various elite to train them in the class they've been chosen for. Once put through all of the various sub-aspects of an individual class, they are tested to see which they are best at after they've had a long enough time training in it. Once said tests are done, they are honored by being named.
Once an In-Training drone has been named, their individuality is actually encouraged as long as it's guided towards helping the hive. And, what they're best at is what's focused on most in their training.
When they've mastered training in that sub-aspect, they are then trained in the other aspects, but during free time away from the training, they are free to experiment with this sub-aspect within a controlled environment, to find more efficient ways to use their Changeling skills for the hive.
Elites are changelings that have finished their training, designated by wearing armor. Since only a limited few are selected for in-training, the elites are even more limited in number in comparison. Elites are usually assigned leading positions in their jobs for the hives, like generals.
As generals, they're often giving orders to the Changelings more than their queen or princesses do, being utilized to ease the strain of ordering so many subordinates in their jobs. A type of hierarchy for commands, essentially.
Occasionally, the routine of ordering other Changelings in their jobs gets slightly rescheduled when drones are discovered for training in their corresponding job class, which isn't that often. When it does happen however, which generals give such teaching is often on rotation, so that the generals are not kept out of touch with their designated sector for too long and are kept well informed of the area they work in. Being kept informed like this makes it easier to return to their old job once training is finished.
Princesses are the equivalent of ascended Changelings, much like how Twilight and Cadance have ascended into alicorns. But, unlike them, Princesses unknowingly have a limitation.
Due to the hive mind, the Queen of the hive subconsciously suppresses ascension to a limited number for those within her hive that have become worthy of such. Through this limitation, there is only one Princess(or on very rare occasion Prince) per Job Class within the Hive.
This suppression is a subconscious restriction placed through the hive mind in order to maintain order throughout the hive. Only through either a princess dying or a princess choosing a successor can a new princess replacement result, while under the control of the hive mind that is.
However, if outside of the influence of a hive mind, the hive mind restriction can no longer prevent an ascension. In those circumstances, all that is needed for the ascension is enough energy to be compressed within their bodies to trigger the ascension.
This energy requirement is needed regardless of whether the hive mind restriction is in place or not. Usually, it's given to an elite based on both their merit and their predecessor's choosing.
Physically, princess Changelings are much like the transitional phase that Twilight and Cadance seem to be in. Basically, smaller variants to Queens. They have the feral pupils, noticable mane and tail, along with their sizes varying from pony to Cadance size based on age.
Along with that, the ascension caused by compressing magic all throughout their bodies has evolved their cells. This in turn has turned them into mini-mana generators, able to replenish their mana reserves just by resting to a limited extent, though they can still increase their mana further by feeding.
This self-mana production makes princesses noticably stronger than normal changelings, and it makes producing eggs a lot easier for increasing the numbers of the hive.
Along with often coming in person to work with those that work under them and training, a princess primarily acts as a manager for her job class. Deciding which Elite goes where, while also having the authority to override the orders of those under them.
And on top of orders, they're the primary source of egg producing. The Queen can technically produce a lot more, but often only lays the bare minimum so as to focus more on the overall well being for the hive. As such, the princesses tend to be the main egg producers.
Being the main egg producers also has the added benefit of restraining them to work off field, allowing them to focus on improving the management part of their work. On-the-job training in a sense. Though, they're still allowed to take part at times on the field to keep their skills sharp.
Queens are in many ways similar to princesses. That includes egg laying, needing energy to ascend, and the hive mind restricting them from ascending without the permission of the one that'd become their predecessor.
Despite those similarities, there's differences.
Differences in Body/Powers:
Queens, unknowingly, are far more powerful than princesses due to a reason that the queens themselves are unaware of. That detail being that they subconsciously feed upon their own hive in small amounts.
This subconscious draining of their hive is kind of like the old concept of gaining money by taking spare change from accounts that neglect them. Individually, pennies, nickles, dimes, quarters, or the like don't amount for much and are considered an insignificant amount. But, take these insignificant amounts from hundreds or more people, and it quickly adds up to quite an enormous sum.
Due to this, Queens are considerably more powerful than princesses, though it is widely assumed the reason is only due to the ascension. It is never asked where she consistently gains the power from. Often, it is considered strictly from her own power. It's true her own ascended cells provide a significant sum of her power, but a large source of power actually comes from this subconscious draining.
And as for physical differences, that's already well known. Basically, approaching Celestia levels of height, skinniness, and the like. Not much to say there that'd differentiate the Queens from the Princesses physically.
Differences in Job:
As the Queen, she must have a general understanding of what ALL the Hive's Job Classes are, along with a general understanding of what they can do. Her knowledge of only the Job Class she originated from not being enough. And, on top of that, she has to consider the hive as a whole, as well as which Job Class is better suited to which tasks.
As Queen, she decides what the hive will aim for as a whole in terms of goals. But, it's also a lot of work, having to know all details of her hive and which to go where, including the jobs that she had a hard time understanding before.
Also as an emergency, a Queen can rapidly mass produce Changeling Eggs, though it's rarely done. Often, this is used should a large number of Changelings be lost all in one go and cannot be reclaimed for healing. Though, doing so comes at the cost of temporarily disabling said Queen from much physical exertions due to the toll on both her energy and her body.
Utilization of Tools:
Due to the Changelings' ability to shapeshift, using tools is looked down upon as a 'pony thing' to do. It's not outright prevented, mind you. But, it's heavily looked down on for their 'predator' species to rely on things that their 'prey' has made and that they have not made.
Basically, it's a matter of pride. If they can make a Changeling variant of the tool that accomplishes the same features of other species' tools, it is fine. But, using tools that a considered 'prey' uses is considered insulting to their superiority.
Or at least, that's what some Changelings thinks. Not all Changelings with individuality agree with this. But, since the Changelings that have the most contact with other species are in the minority, any disagreements to this belief are often overshadowed due to the fact that most Changelings haven't seen how efficient or useful such tools are in action. They've yet to see what great things they can be used for, since great constructs often take time to make, which simple demonstrations to prove a point are not able to prove the usefulness of.
Due to this, excluding the creation of additional, often enchanted, armor, the creation and use of tools are vary rarely seen outside of the hive. As for inside the hive, none have survived long enough to be able to tell tales of whether they have or not.