ok trying to articulate why i really struggle with being able to see canon otacon as transmasc and mostly it's just because i don't really think it makes sense for an afab trans person to have the sort of relationship to his masculinity that he does. i'll preface this with an obligatory disclaimer that this is just me gathering my own thoughts for myself on my own blog and not trying to stop anybody from hcing whatever they'd like...and also it's very late and it's been a while since i've played mgs in any capacity so it's entirely possible my recollection is shaky
i think part of the issue is fanon's tendency (from my perspective anyway) to depict him as being very expressive, an interpretation likely exacerbated by the way that he's written in mgs1, but even then he's generally not very reactive--just meeker, on account of many characters' personalities having significant archetypal influences in that game. overall, particularly in mgs2/4, i would describe otacon as being a very analytical person whose emotions are typically only exaggerated during very, very stressful moments...and when he loses patience with snake, of course. with most people, as is his default, he talks very evenly and intelligently and is not loud.
the real danger comes not in portraying otacon as being very expressive, which is harmless in and of itself, but in letting that bury what is to me one of the most significant aspects of his character, which is that he intentionally and textually suppresses his internal emotions so as to not appear "weak".
this is immediately after the "love on a battlefield" scene, of course. this is the first time snake is really vulnerable with otacon, who in exchange reveals that by hiding, he can not only protect himself physically but soothe himself spiritually; fear is a weakness he can rid himself of by suppressing his entire self.
literally, otacon just doesn't want to be seen as cowardly; metaphorically, it's very easy to make a connection to traditional standards of masculinity societally imposed upon amab people. i think that's enforced by the way that he discusses having been assaulted by julie as a teenager.
essentially, "she seduced me" = "*i* wasn't strong enough to *resist* her". to otacon, though julie is at fault for initiating the relationship, the blame ultimately falls upon him for letting it continue. though i can't really speak on this in detail, it's obviously very easy to make a connection here to the specific pressure placed on and stigma surrounding cis male victims of rape that differs, as is true for most things, from the way victims of other gender identities are societally treated.
otacon's troubles with his masculinity arise as a result of the fact that he isn't good at shoving everything down; he pisses himself, he cries. his feelings cloud his judgment in professional environments. he can't help being terrified after doing everything in his power to not be. he longs for snake's mental fortitude, but regardless breaks down completely when he loses emma and naomi. hence his characterization in mgs4: rather than accept the pain he knows will have to come, he distances himself emotionally from snake (just as snake himself does) so, when he dies, it'll hurt less.
he just reads very clearly to me like an amab person trying and failing to live up to his designated toxic standard, not recognizing that, consistently (throughout all three of his appearances), it is his emotions and readily-sympathetic nature that give him strength and an edge over the people around him.
i think what's most significant is that, in a series filled to the brim with stoic and emotionally stunted characters, otacon's self-suppression is specifically tied to his identity as a man rather than his identity as a soldier. snake is just as infuriatingly shut off, but that behavior stems from the nature of his environment, not the nature of his self; there's plenty of lady soldiers in mgs, but otacon, distinctly, is a civillian. not that gender doesn't play a role in the way militaries worldwide are structured...obviously...but both sons of liberty and guns of the patriots really gender otacon's internal conflict in a way most characters' aren't.
i would be more inclined to subscribe to transfem otacon, but i don't really think he's trans generally...raiden though i do genuinely and wholeheartedly believe is a trans woman. but that is a whole other can of worms. raiden is also on a different level entirely with how significant his relationship to his actual physical body is to his character, something that isn't really there for otacon (i guess the stealth camo can count. but i think that would be a point for transfem otacon anyway)
