Look, I am only a casual superhero comics fan, but here’s my sideline/peripheral take:
When I was two years old, Lando Calrissian betrayed his friends to the Empire. And then he thought better of it and became a good guy again. Two years old. I don’t actually remember experiencing this story for the first time, it’s a thing that entered my brain through cultural osmosis and repetition. I am now almost thirty-nine.
Why do I bring this up?
Because “maybe someone you thought was good is actually bad! but wait, no, they’re actually good again!” is not a new story for anyone who is an adult now. We have all done this one. It is not daring and new, it is not a shocking twist, it is–in fact–kind of the default. Yes, yes, who can you trust, anyone might turn out to be blah blah whatev.
We have never experienced a Superman without a kind of kryptonite that can turn him evil. We have never had a hero without shades of gray. And I’m not suggesting that we should do a ton of that. I’m not suggesting that abandoning nuance is the way to go. I’m just suggesting that “the ground beneath your feet is shifting! who should you trust!” is yeah, yeah, yeah, pretty old hat to more than one generation in a row by now. So you really need something better than that if you’re going to try to convince readers that you have something great up your sleeve. As far as twists go, this is as twisty as “maybe they’re all dead we promise they’re not oh wait they are.” Other people have made the moral arguments already, the arguments based on character background/origins. I find them pretty compelling. I just wanted to say, also? it’s really sad when you go to shock people with things that have been standard templates for longer than they’ve been alive. It relies on one of us not paying attention, and buddy, it’s not me this time.