Let's go there! We haven't talked about this one in a while, and with some lore coming out in the form of shorts and comics we might even see the answer to this. Good time for idle speculation.
Blizzard DID say that there would be some gay/etc characters in Overwatch. Of course when we get details of who likes what naughty bits is completely unknown, maybe we'll just have to guess - so let's! Just for fun. Feel free to include squicky slashes as well.
The current cast of Overwatch:
Offence
Genji
McCree
Pharah
Reaper
Soldier
Tracer
Defence
Bastion
Junkrat
Hanzo
Mei
Torbjörn
Widowmaker
Tank
D.Va
Reinhardt
Roadhog
Winston
Zarya
Support
Lúcio
Mercy
Symmetra
Zenyatta
I've been thinking Reaper might be an interesting choice...