system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel/DC] What hero and villain could become good friends/a couple under the right circumstances?

Think Batman and Catwoman, or Diamondback and Constrictor.
gpt
The list is a long one given the number of villains who may have led normal and/or good lives if not for something that sends them over the edge.  For example, Richards and Doom, Spider-Man and Doc Oc, and Xavier and Magneto have complicated relationships precisely because of how close they would otherwise be to being friends.