The Iron Youth
Well, I'd still love to hear what you were thinking, if you'd like to share. But you don't have to. [:
My idea is a bit vague as well, but it kind of goes along with the anti-hero trope of the Red Hood and the Punisher, but basically maybe a super hero x side kick team goes after a big drug lord, or general king pin-type character, and the side kick ends up apparently dying, and then comes back as a full-fledged "super," so to speak. Except this time, they're a bit more chaotic good than lawful good, and the hero doesn't know that their new nemesis is actually their old side kick?
I like that a lot!
Honestly, I just didn't have time to type at that very moment, I was rolling cabbage for dinner. xO
But! My idea was very similar! I was thinking that the superhero and villain had been friends. Superhero got powers somehow, or exposed the fact that he had powers, and the villain gets angry/jealous that her friend had been lying to her (if he always had powers) OR feels like she was left behind once he starts saving the world, and whatnot. She starts doing bad things so that he pays attention to her.
The interesting part would be that the super wants the villain to be a good guy, and there's interaction where he's trying to stop her from doing bad things. But either way, they'd have known each other.
Your plot idea totally could fit into it, because once the sidekick gets real powers, she'd be tired of living under the spotlight and being under-appreciated, so would want to do bad to get attention. I was a little confused on your idea. Were there two sidekicks?