Yeah, that's how I'd describe it. He prefers women, but won't say no to the right man.

My daughter used the term "hetero-flexible"

Invisible Kid I died in the early 70s, but in a 1990 Secret Origin story, it was implied that he had a relationship with Chemical King (also died in the same era). So it was done posthumously and by a writer who had never previously written the Legion and never would going forward. Nonetheless, a lot of Legion readers have accepted the story.

Basically the Captain Harkness of the DCU?

Pretty much. Except I think Captain Jack leans towards men more than he does towards women. And Constantine is probably the opposite.

Except if you're trans and identify as a woman you aren't a man. If you're a man dating a trans woman that's a heterosexual relationship.

I think Captain Jack goes for whatever has a pulse, but he does seem (especially in Torchwood) to favor the men.

And Max "Electro" Dillion came out of the closet awhile back.

That's quite shocking.

And now the Hulk knows what the noise was at night that sounded like someone banging rocks together.

He did? In the regular or Ultimate verse? Last I remember he was dating some waitress in Boston. Course, this was at New Avengers #1-2 or so.