It's Batman x Harley Quinn one.
The Joker is dead, shot and killed by one of his own henchman. Batman attempted to stop the gunman, but couldn't help in time. This has left one very lonely and crazy significant other behind: Harley Quinn. Blaming Batman for the murder, Harley Quinn constructs an elaborate plan to capture him. After capturing him and leaning over his body, tied up, Harley realizes with the bomb in her hand that Batman is probably the only guy left that's crazy enough to understand her, and so she douses the fuse of the bomb and proceeds to take sexual control of the situation. Resistant at first, Batman eventually can't help himself. This results in a very strange and twisted relationship forming where dominance switches back and forth quickly. Harley Quinn still runs around causing trouble, but Batman cleans up her mess and tries to talk her out of her criminal life. Other complications can be made but this is just a rough patch up. Batman helps Harley out of various tight spots, but where should he draw the line? Will he himself finally cross the thin line between being a vigilante and a criminal?