sorry for always being at the scene when the semantics of his DID is being discussed. im autistic. also i agree w both of you + i love you.
i rambled a bit in the comments, but i think this is worth dissecting.
Most people don't have distinct parts because the opposite is necessary. However, sometimes parts are extremely distinct because it is necessary.
i think theres a spectrum of part distinction that gets overlooked.
on one hand, all parts are 'distinct' because they reflect different sides of the personality. for as long as theres dissociative barriers between them, between part a and part b there will be differences in how they function and think and approach the world, because the barriers are a byproduct of not being able to reconcile conflicting viewpoints or worldviews. the fact that alters/parts exist and are not identical and these differences in functioning and ways of percieving are not faked is a fact.
they also naturally come from the common place of being the same person, so the differences are integrally what had to be different between states, and what could not be shared by the others.
sometimes, 'sense of self' is something that could not be shared between states. this is how you get alters that consider themselves different people. if the way my alter sees the world cannot be reconciled with the fact that i am adult, they will see themselves as a child. identities get subconsciously constructed in this way to help alters make sense of their realities and alienation from their collective self (not to mention many pwDID struggle to identify a collective self due to fragmentation).
mikoto's different alters are absolutely shaped by their unique life experiences and what part of his identity they occupy and serve, and that affects how they present themselves, how they act, how they think, and how they conceptualise themselves.
it's not theatrical for an alter to be honest about how they see themselves and act 'different' to any normative alters. because their part and presentation of the system's personality/collective identity is just as much 'them' as the normative selves. no alter has to act like 'the host'. that's not what healing is about. healing is about understanding how you combine into your collective self. and also addressing the natural consequences of trauma on different parts' functions and self images. because PTSD. low self esteem. this is a tangent. reeling it in.
an issue i find with how the milgram fandom approaches mikoto's DID is through incorrectly assuming that because 'john' is a distinct alter, he must also consider himself 'not mikoto', or must, as an alter, have his own name, or distinct internal appearance. i think this is where theatricality comes in. it's the incorrect assumption that alters are blank slates, and that any differences are not necessary deviations.
(i personally enjoy headcanons about how he might see himself internally or give himself different names. i think that's a fun thought experiment in how alters can conceptualise themselves. but it's really not inherent or something that needs to be considered.)
'john' / orekoto exists. he understands himself, to a degree, as separate from mikoto, because thats how his DID works. his demeanour is different to normative mikoto, because normative mikoto is dissociated from the part of his personality that is contained in 'john'.
but i think a lot of people hear 'alter' and run with it, and assume that because he's an alter, he must also be different in other, more florid ways. and it perpetuates this idea that alters are discrete, and is also just not in line with the text, and suddenly this preconception is overshadowing how mikoto's condition actually presents in canon.
i think milgram fandom would really benefit from reassessing their assumptions about how DID works and what they take as a given. it's fascinating to consider why 'john' distinguishes himself and what his demeanour tells us about the collective mikoto (who he is as a whole / what normative mikoto could not tolerate / what mikoto had to develop a side for but also suppress). and it sucks a lot of people don't think about this! because they think this is just 'how DID works'.
it's why i think the label of DID does mikotos fandom perception harm. without these preconceptions associated with DID or the word 'alter', i think people would be a lot more willing to analyse why and how he developed the subconscious coping mechanisms of suppressing sides of himself, holistically. but because he has DID, it's 'just how it works', as if he was born like that, inherently different.
anyway i love this discussion and i think there's a lot to be said. i just really think questioning the language we use and the connotations of it, and encouraging people to use accessible and more varied vocabulary is really valuable for combatting these issues. ok thanks for letting me ramble lol.