1) AU-magical. Harry was never placed with the Dursleys' as a baby but instead taken on grudgingly by Snape who feels obligated to care for Lily's son. He eventually comes to genuinely like the little brat and adopts him. During Harry's years at Hogwarts, however, Snape's feelings start to change again and become very inappropriate. I'd like them to have to fight disapproval for their relationship when they can no longer keep it secret, especially because of the quasi-incestuous nature of it. Angsty, but with happy, or at least hopeful ending.
2) Another AU-magical. Voldemort never existed, so Harry's parents are alive. How do they react when Harry forms a relationship with a Professor who has always despised and belittled him?