Time Travel Prompt: Harry ends up (somehow) on spinner's end at the same age and time that Lily and Severus met and talk for the first time.
Silly Prompt: Harry and Severus watching "True Blood" or "Twilight" or something to do with the vampire novels together.
Dark Prompt: Severus loses his cool in a cruel way with Harry at whatever point.
Kinky Prompt: Severus takes courage to ask Harry to spank him. (I never saw one of those...)
AU Non Magical Prompt: Severus is a butler, Harry is the son of the master of the house that can't control himself. (I would like a very dignified Severus.)
AU Magical Prompt: There were never problems with the dark and the light. It's animagus that is the problem. Severus is a snake and Harry owns a pet shop (or something) and finds him.
Another AU Magical: Severus hears the entire prophecy.
Again another AU Magical: After Lily dies, Severus can't take the pain and takes a de-aging potion and starts all over again in the care of Dumbledore or Lucius. You pick.
Cliche Prompt: Harry and Severus have to marry/bond/have a baby for Harry to have a magical boost and defeat Voldie.
Weird Prompt: Harry Potter has a different aging process. He ages 2 years for every 1. And that counts his intelligence too.