if you could explain how your physical shifting works that would be great!
I understand phantom limbs etc - but reading your posts has been a bit confused and I would love to understand better :3
(obvs only explain what you feel comfortable with)
just gonna preface this with: we're& only questioning being pshifters so we don't know if what we experience is related to pshifting! we use the term "physical morphing" for our zoanthropic/physically plural transformations instead, out of respect for pshifters cuz they already get lied on enough intentionally or unintentionally. if you want to know more about pshifters from pshifters themselves, i linked a few posts/blogs i learned from in this post.
anyhow, to answer your question... morphing is spiritually-rooted to us. stag and i express separate strains of zoanthropy because his deer morph was put on him as a curse before his soul came to this plurality, but my soul was reborn within this body naturally carrying a canine imprint from a past life.
when the first entity born to this body passed this flesh to me and stag, it was still physically human. stag was more dominant at first, so it morphed to reflect his man/deer forms instead of my shapes. when i reclaimed it later, and accepted my fate as the first entity's successor, the body's default morph permanently changed to werecanine to reflect my soul's form. after reforming my bond with stag, the body regained some access to his different morphs. mainly growing antlers.
i am outwardly human-appearing, but the substance of my body is entirely weredog-wolf. because of how energy-intensive morphing is, most of the changes that happen in an episode stay more internally salient than externally visible. bones skewing, inner-muscle stretching, nerves firing while rerouting. i might startle and yelp and lose my humanized speech because the finer muscles in my mouth and throat turn clumsy. it hurts in a steady-grinding half-distanced way, like getting dental work done on some but not enough novocaine. but the shock lingers more than the pain.
morphing is more involuntary than voluntary to us. we can't stop it when it happens, just try to slow and steady the changes if we're not alone, and then make way for the transformation and reversion to air itself out once we are. going into dazes/trances helps with staying calm even when it's overwhelming, especially when my mind goes more instinct-centric and loses comprehension of the transformation my body is undergoing. dazes and trances also help with more voluntary morphing, but force and desperation drives it away.
stag's and my morphing has only been visible to those willing to see as far as we know. i say "as far as we know" cuz there's been a few berzerker incidents we can't remember enough to make heads or tails of. but stag's antlers have been visible to one other person on a regular day before.
unlike me, stag keeps his sapience more often when he morphs, since he stays more human or were than theriform. since stag belonged to a separate body before becoming part of this plurality, it's harder for him to physically morph with this one. but still, sometimes his presence pushes the body to partially morph my features to his--antlers budding, hide changing texture, foot and ankle bones trying to go unguligrade under skin that won't give.
there may or may not be a genetic/biological factor involved that makes this body more species-malleable, but inborn genetics/biology also might not actually be necessary for us to morph. in chinese lore, any animal in the animal world can self-cultivate a path to disguise as, or reincarnate among humans on purpose. and in buddhist lore, you can even self-cultivate a path to move from the human world to the animal world in the next life, becoming as a theriform. it is also not unheard of for an animal spirit's possession to reshape a human(ized) body into something more beastly.
if there's any other questions / specifics you want us to answer, feel free to drop another ask!!