1. How about some fairy tales? There are some nice fairy tale snarries but we can't get enough...
2. There is a potion incident and Snape finds himself fallen in love with The Boy Who Lived. But all of his other faculties are intact so he doesn't act on it. Harry still hates him an he needs all of his Slytherin cunning to change this. He find help from an unexpected source.
3. PostWar, EWE. Snape disappeared from the Shack. Dumbledore left him a small warded and unplottable house. He lives there and tries to heal the wound on his neck. He manages to create a special potion for it but the effect is temporary and the wound opens again and again. His only contact to the Wizarding World is Minerva. She tries to persuade him to visit Harry who became a very powerful healer.
4. AU/AR A powerful evil wizard kidnapped Harry (17), keeps him in his castle and wants to marry him but Harry doesn't give in. He has free access to everything in the castle except 3 doors. When the evil wizard leave the castle Harry tries to peek behind the doors. There is a magical device behind the first, a magical creature behind the the second, and a very thin sleeping man with slightly greasy long black hair and beaky nose behind the third. Harry visits him regularly, developing feelings to him. He finds a way to use the magical device for some sort of communication with him and tries to free him with the help of the creature. (The creature can be a good one like a phoenix imprisoned by the Dark Lord or an evil pet like Nagini and tricked to help them)