Summary: Something happens (you choose what and how but make it plausible), and Severus ends up in an alternate timeline or universe. The timeline he left was one in which he had adopted Harry (you choose how long he had had custody of Harry) and they had a loving relationship. The timeline he finds himself in is the one we know and love from canon. He finds himself in a timeline where he and Harry are bitter enemies. Severus can't find a way back and he can't reconcile himself to leave his relationship with Harry as it is in this new timeline. He also can't watch the Harry of this timeline continue down the self-destructive path he's on without a parent because he loves him too much.

Rules:
1. Make it plausible.
2. Make it realistic. No rushed relationships.
3. Keep Snape and Harry in character. I hate reading stories where their dialogue is unrealistic for their characters and when they do things their characters just wouldn't do.
4. No slash.

Other thoughts:
Snape probably tells Dumbledore at some point what's happened and where he came from as that would just make things easier (and actually more interesting as Dumbledore probably finds the concept of Snape having adopted Harry in any universe an interesting one). Preferably I'd like to see a story in which Snape does not return to his original timeline and doesn't think overmuch on 'his' original Harry. Maybe something happened and the other timeline was actually destroyed, so 'his' Harry isn't left wanting for his father in another time and place. I also think it would be more interesting (although it's up to you) to have Harry be 13, 14, or 15, so he's a teen and his personality is already set. I can't see it being all that interesting with a younger Harry and if Harry is older that doesn't leave Harry any room at all to see how having Snape as a father figure would be beneficial as he'd be almost an adult by wizarding standards. All other details up to you. I'd love to see multiple entries for this challenge.

Summary: An abused Harry discovers there are house-elves, and that these creatures do all the cooking and cleaning. Since Harry had been treated as one for as long as he could remember he decides to join them in their duties. I would really like it if Harry starts living with the house-elves and refuses to go back to his dorm.

Summary: What if Harry isn't James and Lily's child, but James and Severus'? Bonus if Sev is Harry's "mom".

Summary:

Severus or Harry (or both) have an allergy. Litterally, that's it.

BONUS:

*How severe is the allergy? Is it Epipen level or is it more of an intolerance? (If you have both, are their allergies on the same level or different?)

**Include how they deal with the allergy (how does the magic world deal with it? Spells? Potions? Magical Epipen?)

***If Harry and Severus both have the same allergy.

Summary: Crossover/fusion with Call the Midwife. Plot is author's prerogative, but it must have Sister Evangelina yelling at the Dursleys (and possibly Snape) for their treatment of Harry.