Since Satan isn’t real, we’ve never much cared whether media depict him as “good” or “evil”; not like he’s going to mind. But that may change.
Theology and fiction sometimes speculate about whether god will ever redeem Satan. This question ignores the more important fact that that’s our job.
Napoleon once demanded where god is in math. Fundies want to know where he is in Satanism. These are dumb assumptions, but we all make similar errors sometimes.