Bear in mind that both your comment here and the one you are replying to are from the perspective of how you view people. The discussion is more on whether that person's personality and character will be affected by being gay, not whether you will treat them differently.
Now for my two pennyworth, yes if I'd been straight I'd be different to how I am now in more than who I choose to shag and what dubious internet searches I perform. However in terms of how a video game character in an epic action story is portrayed, I'm perfectly happy if their sexuality has no significant effect. In that specific context I'm happy with the idea it doesn't make much difference.
Of course it's from the context of how we view people. That's the only context that matters when discussing a character we will only observe and interact with rather than inhabit and direct. Sera isn't a POV character. She wasn't written as a POV character. She was written as someone we will interact with as a separate person, and in a relatively specific situation at that. We aren't going to live through her wide-eyed youth, discovering the world, or her awkward adolescence when she's discovering herself. We meet her fully formed, as one world shaping killer to another on a quest to do said shaping, and none of that history ever needs to come up. It is highly unlikely she's going to introduce herself as "Hi, I'm Sera. I kill people sometimes and I'm a lesbian". I find it far more likely, if she says anything about it outside romance options, that it will be throwaway banter, or a Lileana/Majorlaine backstory that directly effects her ability to continue our primary goals.
As much as I dislike DA2 Anders, I can appreciate how his bisexuality was handled. Namely, that you would never know unless you played both genders. I saw someone, maybe in this thread, talking about how he 'hid' his relationship with Karl from FemHawke, and I actually laughed. He didn't hide anything, it just never came up, at least not on screen. And honestly, why would it? If he didn't define himself by it, why should we?
I look at Sera the same way. If she doesn't define herself by her sexuality, why should we? I'm always seeing how people are up in arms about homosexuals, men and women, being terribly written as stereotypes, or damaged goods from bad relationships, or who's only important characteristic is that they are 'the token gay'. Here, on the other hand, we have a writer outright saying he wrote the character as a full person. And part of that full person is homosexuality. Shouldn't that be a breath of fresh air? Something to be lauded rather than "Oh, well, you could never write a lesbian properly". Damned if he does, damned if he doesn't, here.
It's like people are searching for something to whine about. Oh, right. Internet. Carry on.