Dorian in Dragon age Inquisition would be a good place to start. One of the few times that a developer has went out of there way to force a characters sexuality, all ham fisted like and I had no problem at all because he was a good character and his sexuality didn't define him nor did he make it any in your face sort of a deal or say 'hey, I'm gay' within five minutes of interacting with him. Just a cool gay dude and a solid character all around. Sara from that game too who was bi seemed decent but it was difficult to make sense of her character at the best of times. Maybe, Gay Tony also as a good example.
I can't think of many more that havn't either been a retcon (Ellie, who is a good character just, seemed like they saw an opportunity like JK Rowling with Dumbledore and forced it in after the fact for the whole 5% of people who played left behind next to the main game) or handled very badly (everything in Mass effect Andromeda from what I've seen). I'd say the main thing you should note is that a character does NOT have to be defined by their sexuality or make it known. I remember seeong one Mass effect character litterally say they were gay or Bi or something in small talk right as you met them. If anyone did that in real life I'd find them veey strange and if they droned on about their sexuality I'd find the quickest escape route possible, thankfully no one does. ...I hope. Even though people are defining themselves more and more around who and what they want to hump or have between their legs, it makes for a very boring character and can push any positive message of representation to spite for the gamer.
Everything in the above reply is my opinion, from my own perspective and not representative of reality outside of my own head!
-Android user, please be gentle with critique on my spelling.