Lust. Not even a question.

Author: What? Why? Wait, don't tell me you two would be bang-

No we would not! We're siblings you disgusting pervert! *clears throat* Anyway, it's because she's the most tolerable. Gluttony would complain about being hungry, then eventually try to eat me. Greed has an annoying face to look at. Envy is a non-stop chatterbox of stupid taunts. Sloth is just....dull. And I've been with Wrath for long enough as it is, pretending to be his damn son. Next.