In The Witches of Eastwick, Nicholson uses his Satanesque sharp teeth and pointy eyebrows to seduce three reasonably attractive, uptight New Englanders (he's not explicitly referred to as Satan, but it's pretty obviously him). He teaches the three women to unleash their inner powers through magic and silly amounts of sex. He then offers them a huge mansion, nice clothes, happiness and the courage to be sexually independent beings. He also teaches them to fly.
It's probably a metaphor or something.
The only catch is they can't talk about him behind his back ... which isn't so much a "catch" as it is a pretty standard understanding between friends.
Why He's the Good Guy:
Unlike most devils, Van Horne doesn't want to bring hell to earth or destroy humanity or even to take anyone's soul for eternity. The only thing this Devil wants is to party with some MILFs in a mansion without worrying about whether they're insulting him when he's not around. Companionship. That's it. That's what he wants.
Is the occasional foursome with beautiful movie stars really so much to ask?
Yes, by the end of the movie he's going all-out Devil on the girls, using magic and shit to harass them. But he was kind of pushed into it.
So what went wrong? A few things. When a nosy neighbor decides to talk smack about the Devil, he suggests the three women curse her with the misfortune of vomiting cherry pits. So, it's more of a prank than a curse. It's mildly gross at worst. Unfortunately, nobody involved had any idea that their victim's psychotic husband would freak the hell out over her illness and beat her to death with a fire poker. That's not the sort of thing you can predict, even when you can fly.
Pokers: For when your insurer refuses to cover mental health problems.