Summary: Severus falls back into old habits. Somehow Harry is involved helping him out of them.
Idea 1: After discovering the Dursleys/Umbridge/someone else is/has been hurting Harry, Severus kills them.
Idea 2: Dumbledore lets Severus take the DADA post, but his fears of it bringing back out Severus' dark side are proved correct.
Idea 3: Voldemort discovers Severus is a traitor, but rather than instantly kill him, decides to try and turn his loyalty back.
Idea 4: Dark magic is an addictive substance. Severus has been using some sort of drug to control his cravings, but now there's a problem with the supply.
Or anything else you can think of!
Any category and point in canon goes. No Dumbledore bashing. No slash. No dark!Harry.
Bonus points for a story involving more than one of the ideas. Extra bonus points for one involving all four!
Summary: Harry himself is killed, but he can't die due to the Horcrux within him. This leads to the discovery that Harry is a living Horcrux, and as such he is immortal unless killed by a basilisk tooth, the sword of Gryffindor, or the Dark Lord's Avadra Kedavra.
Summary: Harry is cutting after the war while trying to complete his Hogwarts education. Professor Snape follows him on the one night he goes too far, catches him, and heals him.
Summary: Professor Snape has his Fifth Year students brewing a minor truth serum that will have the strength to have a person tell nothing but the truth for roughly ten minutes. Harry is "volunteered" to drink it.
Must have the Dursleys and Umbridge revealed and Snape becoming Harry's Guardian. Kudos for anyone that has an understanding!Sirius and a highly manipulative Dumbledore.
Summary: Takes place 5th year. During class there is an accident and several students are splashed with potion. Snape lines all the affected students up to assess damage and administer antidotes as needed. Harry has gotten slashed all over his arm and hand but attempts to hide his hand (possibly already bandaged) with Umbridge's scars on it. The damage from her quill could be worse than in canon or she could have used other forms of physical punishment on Harry as well. Snape eventually discovers the damaged hand. What will he do about it? Could be slow developing and Snape doesn't take an immediate liking to Harry, but stays in character.
Summary: Petunia and Vernon's marriage has fallen apart, and she's leaving him with Harry and Dudley. For a lack of anywhere else to go and/or to hide from Vernon, she goes to Snape. He is naturally shocked to have the three of them turn up on his doorstep. What happens next is up to the author.
Abuse could be involved but not required. Category and canon placement up to the author. No Dumbledore or Lily or James bashing. AU backstories welcome. No slash.
Summary: When Harry begins Hogwarts, his childhood imaginary friend is still hanging around.
Summary: Pre-hogwarts (but school age), Tobias is still alive and lives at Spinner's End. Social services determine living conditions to be unfit for Harry at Privet Drive after reports of neglect/abuse. He is promptly deposited at Spinner's End where records show his father lives and is forgotten about. (Severus or Tobias can be his father. If Tobias, I'd imagine through some not so nice actions to Harry's mom Lily). Tobias does not treat Harry well, is drunk and abusive/neglectful. Severus, who lives elsewhere, has some type of reason to (unwillingly) stop by his childhood home and discovers the boy lurking in the corner. Who is the kid? What, if anything, will Severus do? Not meant to be a nice story, nor immediate resolution.
Summary: Hermione and (a reluctant) Ron reach the conclusion that Harry is in need of a parent/guardian. After a through analysis by Hermione it is decided that Snape would best fit the job. They set out to create as many situations for the two to bond as possible and to present Harry in the best possible light. Snape and Harry are of course unaware of the plan. Will they succeed?
Summary: After at least one year of knowing and hating each other, some incident causes Harry and Severus to bond and become close enough for an adoption to be planned. But then tragedy strikes--all of Severus' recent memories are erased, leaving him with no recollection of the incident, and once again despising Harry. No Dumbledore bashing!