I have a question about changelings in general, are they able to sense other changelings nearby even when they are in disguise? And to build on that can changelings sense whether they're from the same hive or not? If so, how does it work?
That’s a good set of questions. With how much changelings rely on stealth and secrecy, there has to be some way that they aren’t tripping over themselves all the time. Not good for long-term survival if you keep tripping over your own secret agents. Or worse, a rivals’. So how do they keep track of each other, even when in the field?
Those big bug eyes of theirs can pick up wavelengths of light that normal ponies can’t. What’s more, they can emit this light even when disguised. While it’s possible to use magic to detect it, suffice to say Changelings haven’t given ponies many opportunities to study the phenomenon. Any means of detection is likely to be unwieldy, or very narrowly known.
In any event, this glow has a couple of uses:
-Alerting other disguised Changelings of their identity, without giving any sign that might alert a potential mark. Now, you might think that this would be a liability, alerting other, potential rival hunters that a game is afoot. I’m going to go into this a lot more when talking about inter-hive relations, but simply put, messing with another Changeling’s con is a good way for both parties to go home hungry. Much better to pull back and find easier prey. Besides, Changelings tend to shy away from that sort of direct confrontation as a rule.
-Cave ambushes. These bugs rely heavily on trickery and theatrics to defend their homes. When unwanted guests are nearby, their scouts need to relay information, and their strike teams need to coordinate their timing if their tricks are to be of any use. If they used chirps and clicks and other buggy noises, then that’d tip off the intruders that something was up. By pulsing their lights, they’re able to communicate amongst themselves silently, leaving their targets in the dark.
-Determining hive identity at a glance. Every Queen has their own, unique coloration. All Changelings of their hive will share that coloration, to include their bioluminescence. This is a lifesaver in the field, as it allows them to quickly find allies, as well as warn off potential enemies, all without risking discovery.
So where does that leave Summer? Can he light up like a parasitic Christmas Tree? Like with many traits of his buggy parentage, it’s a mixed bag. He too has a glow that shines through his disguises, but it’s faint, and he doesn’t have the ability to shut it off. A fellow Changeling would be able to detect it at close range, and understand that he’s only part Changeling and not a Changeling in a unicorn disguise, but at a distance it’d be harder to tell. Likewise, he can see the glows of other Changelings, but it’s difficult for him to pick out details, and he needs to be close in order to distinguish hive colors clearly. In practice, it means that he’s able to easily see and be seen by Changelings nearby - think people in the same room vs. people across a wide street - which is enough to ensure his way of living isn’t disrupted by unexpected family reunions.
