I know it's been said, but power always works for me.
In a 19th level 3rd edition game, I had a PC thief who was CN. Her backstory was that she used to be a multiclass priest of Mask (in the Forgotten Realms, the God of Theives) but had her priestly power stripped from her by the god for no apparent reason. (It was actually because priests of Mask have to be evil aligned and my DM does not allow evil characters.) Because of losing her powers, she shifted in AL from CE to CN (and I started playing her). She was a greedy thief, yes - but wasn't all that interested in money or magic items. She stole more for the thrill of it than anything.
Well, long story made way too short, but the party got sent back 3000 years into the past. While there, the god of thieves at that time (Shar) offered me "the path to power" if I just did one little thing for her. (FYI: never trust a grinning DM.) That little thing was killing the NPC of the group (a priest of Mystra, goddess of magic). So I traveled with the group for a while, we had a big epic battle in which the NPC played a big part, my thief killed her, and the whole party besides me got sent back to thier own time. Later, the party found out that my thief had become the Serif of Thieves (sort of like the arch-angel of thieves). In other words, had been given part of the goddess Shar's power.
There's nothing like the temptation of a god's power to sway a villian.