I have a very specific headcanon about Alhaitham- specifically relating to his gender.

He is AFAB. He does not care. He is not even inherently masculine. He is not feminine. He doesn't really consider himself androgynous, either. He doesn't care. Saying Agender or non-binary doesn't work either, because he's not those either. That's implying he has some kind of self-identification, when really he's completely opted out.

Alhaitham doesn't care about pronouns- He, She, They, there's no preference. Most people default to "He" as... well, it's an accident, really.

He wears binders as he finds his chest in the way and obnoxious, but not enough so to warrant surgery. They also serve some purpose in his comfort, so there's no reason to do away with them fully. He uses estrogen/hormone blockers to stop his period and other side effects of an AFAB body that are not exactly convenient. He cuts his hair short as it's a pain to handle- if it's more than a comb running through his hair it's more effort than he's willing to put in for something he cares little for. Just because many of these things make him appear masculine, none of it was intentional.

He also doesn't wish to have bottom surgery as, while 'wetness' and going to the bathroom might be a little more cumbersome [key word: might] than if he had opposing equipment, he finds the benefit of not having an additional part of his body to need to maintain and position and, god forbid, get hurt by a very precise kick.

Alhaitham doesn't care about gender, nor how he presents. They're just... a bother to him at best, a burden at worst.

[This is a great confusion to Kaveh, who experimented with being a transwoman in the past only to affirm his connection with masculinity and a renewed appreciation for feminine beauty, is incredibly confused by Alhaitham's complete lack either way. He respects it, even if he doesn't understand it.]