If Rey Mysterio returned, would you want to see him have a respectable face - face feud with Kalisto, or one of the two turn heel and feud? If heel, then who would you rather turn heel?
If Rey Mysterio were to come back to WWE, I'd be more than down to see him feud with another Luchador such as Kalisto. Can't even imagine the in- ring chemistry these two would have. I'd have Rey Mysterio turn heel right off the bat, because nobody would expect it at all. Yes, seeing Rey Mysterio heel is like seeing Bayley saying "fuck", but that's what could be so shocking about it. I'd also go as far as having Rey Mysterio and Kalisto doing a double turn after their first match together, having Rey go for a handshake to pay respects to Kalisto after a long, great match, then have Kalisto attack him. This feud could go down in any way possible. Hell, make a storyline where Kalisto is jealous of Rey Mysterio and wants to be the dominate Luchador in the company so he's the heel in the storyline. Hope we can see this feud one day, it would be amazing.