'Just fuck me up, please' is the best phrase to end this gorgeous prompt. I can't promise anything, but hypothetically how would you feel about crossovers?

Are there any crossover characters that you would absolutely not want to be Matt's ex? I'm feeling Marvel bad guys taken out of context, but if you have a huge soft spot for someone I wouldn't like to do that to you.

(Also kind of feeling a weird mirrorverse Captain Kirk coming on?! Maybe the horrible man in the second episode of Cabin Pressure?! De-aged Hannibal Lecter?! The Joker?! I don't know what's going to happen based on these impulses. Please guide me in this.)