Disclaimer: This post is about headcanons, which means “things that somebody likes to believe about the story, that arent confirmed by the writers”. I know none of these things are factually in the story, and i dont expect them to ever become canon. These are just my own ideas i project onto the story because they just make sense to me, personally.
Also, not everything needs to be about gender and sexuality, of course. But it is a topic that is very dear and interesting to me, so im making a thread about it. If you dont care, thats totally cool.
Ok im gonna go by heroes, and first list facts, then list my headcanons that come from those facts. I dont go over every hero, just the ones that i have something to say about thats not canon.
Moira
facts: she is an androgynous woman, an extremist scientist, an individualist, and her technology to rearrange human cells goes far beyond whats possible in the real world
headcanons: Moira is a butch trans lesbian. I love seeing trans characters that dont fit the stereotypes. Shes flamboyant, but shes still butch. Shes a woman, a trans woman even, but also loves wearing short hair and looking androgynous like that. Shes also kind of a trans-medicalist, her internalised transphobia makes her think that in order to “truly” transition, she must alter her cellular makeup to fit a “natural” woman as closely as possible, even going so far as to altering her DNA.
(the things i put in quotation marks would be things she, as a character, believes. they dont reflect my own beliefs)
Omnics
facts: they are artificially created in omniums and dont reproduce sexually. they have their own cultures and religions.
headcanon: most omnics identify as nonbinary, since gender would be pretty meaningless to a being like them. in fact, they dont think of gender much at all, unless they really want to fit in with humans. most of them dont care whether theyre referred to as female or male or anything else. an exception would be Echo and Orisa, because they were made by human Women, who they closely bonded with. Their femininity is their connection to their creators (in Echos case even more than Orisas). Zen, Bastion really dont care about gender at all and will accept any version.
Zarya
facts: she has short pink hair, and is very large and muscular. she looks somewhat androgynous.
headcanon: shes as cis and straight as can be. she doesnt mind playing with gender roles a little, in a joking manner, but is very secure in her identity as a straight woman. she admires muscular men in a competitive way, but for a relationship she doesnt really care about that. she is all about the heart and soul of a person.
Sombra
facts: shes referred to as female.
headcanon: she kinda identifies as nonbinary, but is also too socially awkward to bring it up. working so much with computers and omnics made her realise how meaningless gender is to her, and she softly expresses it with her hair and fashion, using silhouettes that are somewhat feminine but also edgy. shes still exploring herself and goes by she/her pronouns at the end.
Symmetra
facts: shes… a feminine woman? not much here
headcanon: symmetra identifies as pansexual. she believes that any person can be beautiful if you bring that beauty out with the right approach. its all about the effort though, so shes very particular when it comes to style, hygiene, etc. she also has the capacity to become a dom, but maybe shes not quite there yet.
Mercy
headcanon: theres not a queer bone in her, but shes a great ally and supports people of all identities.
Reaper
facts: his condition was caused by moiras technology.
headcanon: turning him into a wraith wasnt her only experiment on him. he grew up in rather homophobic surroundings, so he always hated his gay self. since moira is pretty unscrupulous and has her own issues with internalized transphobia, she tried to relieve him of his pain by trying to “turn him straight” on a cellular level. it failed though. hes a tortured soul, for a lot of reasons. he hates himself, but also hates himself for hating himself.
Im sure i forgot some stuff but thats already a lot and i hope somebody reads and enjoys! also feel free to post your own headcanons about gender and sexuality here! and remember, no headcanon is right or wrong because its all just our own ideas and we can imagine whatever we want 
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