For people who generally stick with one sexuality for their characters (for examples, I mostly just play straight ladies): Are you playing your own sexuality OR are you usually playing something different/opposite to your real self? Is it a comfort thing, interest thing, or trying to experience new things? O:
I haven't checked my profiles in a long while but I think I have a lot of them who are straight women, and it's definitely a comfort thing because I'm straight female as well. I also think when it comes to smut scenes people tend to write about what they know, and what they like because it's easier to write smut that way. Now I feel more comfortable writing characters that aren't straight females because I like to experience the stories through different characters as well...(Although I may not be that good at writing them, lol. I still enjoy it.)
For me writing about sexuality isn't just about inserting slot A into slot B. For me, sexuality reveals another layer of their personalities, their values, and how they see themselves, their roles.
For example
I have a female character who is bi sexual but she treats the genders differently; with men she's aggressive and dominant because she feels the need to stay in control of them, to make them feel what its like to be woman in a man's world. To do and say as she does, without complaint, with a smile, and with a thank you. With women she's much more softer and protective. it's like she becomes the man in the relationship. To treat them like women should be treated, like she wished women were treated.
Another character is bi curious. He feels safe with women because he grew up with them, it's easy to be with a woman for him. He knows how they think, he knows what they like. It's easy...it's great...it's...something. He always has that little voice...
"What if?"...
"Should I or shouldn't I?"
"Am I or am I not?"
"Why is he looking at me like that?"
"My god, he's gorgeous."
"Omg, he's coming closer!"
"...He smells expensive..."
"omgomgomgomg"
"yes no yes no yes...wait no...yes!"
"I'M LATE FOR A THING! I HAVE A THING THAT NEEDS....THINGS!!!"
"Exits hotel"
Then I have another character who uses sex not only for pleasure but as a weapon. All shall bend a knee one way or another. He's straight but if he were to find out that a man had a thing for him he would not hesitate to use that against him or others.
Sexuality reveals more than just kinks for me. It's a glimpse into someone's psyche.