Treacle Worshipper

I'm not sure how Biblical it is, but there seems to be a part of some Xn worldviews that puts the devil in charge of hell. (See, for instance, C S Lewis's The Screwtape Letters.)

If Satan is rebelling against God, how come he gets to be in charge of God's prison? Surely by torturing unrepentant sinners, he's doing what God wants - because God wants unrepentant sinners tortured for eternity.

(Please note: I am aware that not every Christian believes in a literal hell, & so on.)

TW