Hey there. I saw your post and it did fit in with a plot idea I had in mind involving an established superhero emmasculated and dominated by their archvillain. Im still fairly new to e but have started a similar thread recently in elven maiden vs. Human barbarian.
The first idea involves Superman and a pink kryptonite created by maybe Mitzelplex that turns him into a horny slut.
The second involves an aging captain america who is losing his edge. Given the opportunity to get a second dose of superhero serum, he is tricked into taking a supernatural steroid that turns him into a woman. Steroid ball shrinking and breast growing taken to the extreme. Here is a pic of the cap I had in mind.
The idea is that your villain is an archvillain if my superhero and made ellaborate plans to have revenge in the most embarrassing way.