I think the Dresden Files books (particularly the most recent one - Skin Game) demonstrate pretty well that a Warlock can be a good guy. Mild spoilers for those who have not read it yet and don't want to be spoiled: [sblock]Not that Harry Dresden is a Warlock. But his patron is an evil (or at best neutral-nasty) Fey, and the Winter Knight portion of his powers comes from her, along with certain evil (or at least neutral-nasty) impulses he resists as best he can. But he remains good, and goes on missions along with evil people and manages to stay good while thwarting their evil plans.[/sblock]