1. A revamp of Dorothy Sayers' novel Gaudy Night, in which students at Hogwarts are competing for a prestigious academic prize. Headmaster Snape discovers that someone is threatening the competitors and that "accidents" have been occurring. Enter consulting detective and man-about-town Harry Potter, engaged by the Board of Governors to discover who is stalking the students and why. Bonus points for a Harry and Severus version of Peter and Harriet's declaration scene.
2. Harry and Severus have been together for years, but Harry refuses to consider bonding, even though he clearly adores Severus, and Severus feels the same about Harry. Why? And why is it so important to Severus that the bond take place?
3. In the aftermath of the defeat of Voldemort, the government of the British Wizarding world falls. Severus Snape, as headmaster of Hogwarts, becomes the de facto Minister of Magic. Harry, broke and at loose ends since the war ended, comes to Snape to volunteer his assistance. Snape is more than happy to find him a position. Or two. D/s would be lovely.