Maybe you can tell, I'm terrible at backgrounds...
I tried to paint them sitting on something, but I have no talent or patience for backgrounds, so I used the Superman/Batman comic logo so they wouldn't just be on white.
I got into this pairing after watching the Superman/Batman movie, then watching Justice League straight through from the beginning, then reading the Superman/Batman comics.
Update: I know it's gay. That's what slash means. You don't have to tell me.