Gender/Sexually/Romantically Fluid Characters

Characters who have a fluid gender, sexuality, or romantic orientation aren’t seen often in the RP/SG section. One factor in this is likely how many of us aren’t certain how to portray it. We may know how we envision our character, and how the fluidity may come into play regarding the character’s personality or background, but actually portraying it in the RP or SG is different, and seems much more daunting of a task.

Have you ever portrayed a character who had a fluid gender, sexuality, or romantic orientation? What was it like to portray that character?
If you haven’t, would you?

This is the place to discuss these types of characters, so if anyone has advice for those of us who experience doubt and uncertainty in how to portray these aspects of our characters, please feel free to share. And anyone can feel free to bring up their questions on this here too, since you’re likely not the only one who’s ever wondered about an answer to that question.