Okay, hear me out.

One player controls Deadpool. The others control the voices in his head.

By influencing Deadpool's actions, the voices can eventually take control of Deadpool's various sidekicks. Taskmaster, Agent X, and Bob come to mind.

I think we'd be using the Apocalypse World engine, slightly modified.

Have you considered Everyone Is John?

Second that for Everyone is John. It would be perfect for what you are trying to do OP.

Yeah. Everyone Is John is a system that basically is exactly what you described, just without the Deadpool angle. Still, I could see it being a fun game.

No reason you can't run Everybody is John without John being Deadpool.

We could call it "Everyone is Deadpool."

link to another game