Can't remember much of this one, Hermione and Severus marry (I'm prety sure its a marriage law thing). Severus is some kind of wizarding aristorcracy (maybe even royalty) higher than the Malfoy's, at one point Severus tells Lucius that the Malfoys couldn't even hope to reach the social standing of the Snape family. They live in a place called Elysium or Avalon.
The only other things I remember are Hermione being take to Snapes home in a carriage and being made to stay in her own rooms while he returns to Hogwarts, there is an episode when Snape gets jealous and I think he rapes Hermione either non-con or dubious-con.
Not much to go on I know but if anyone has any ideas I would appreciate it.