the worldbuilding dump no one asked for but i’m gonna do anyway
The bulk of (conscious) aenke shapeshifting has to do with how close the connection between mantle and body is. The mantle is basically a “soul” of emotional energy that pilots the physical body, it’s the “true” aenke acting on the physical through a rather arbitrary body. Pushing mantle and body closer or further apart alters the shape, and is usually a willing, conscious process. (referring to them as “further” or “closer” from each other is also arbitrary, as there isn’t a literal physical distance between them due to them being in different dimensions, but hopefully it gets the point across)
Most aenke spend basically all of their time running on neutral, with the mantle and body a safe distance from each other and putting no extra stress on either the body or the mantle. This is usually the generic tailed, unguligrade humanoid that aenke mostly come in.
Pulling mantle and body further apart results in a divergence, which is usually visually similar to the neutral form with some tweaks. Reincarnated aenke usually have a diverged form similar (or identical) to what they looked like pre-incarnation. Going into this form can also trick mortals into thinking you’re one of them, causing this form to sometimes be called a disguise. However the guise falls apart after a few hours for most because, with the mantle supplying the energy for the body, this form puts stress on the now energy-deprived body. Prolonged exposure can cause mortals to start to see through the disguise on their own as well, creating something of an “uncanny valley” vibe.
Pushing mantle and body closer together creates a convergence, which is usually very different from both neutrals and divergences. Not all aenke have a convergence form available to them, as this form stresses both body and mantle and is physically and emotionally painful to change into. Usually caused by emotional heights or extreme emotional stress, the convergence form of most aenke is considered extremely volatile and largely uncontrollable, so those under stress are usually proactively calmed to prevent unwanted convergences from happening. High-ranking aenke such as Diri Mah, however, are generally stuck in their convergence form, and have a very good handle on themselves in such a state.
This is also ignoring unconscious shapeshifting, which has to do with how an individual feels about their body, and is the root of most of the more subtle shapeshifting (such as body type, height, or proportions changing).