In the Deathly Hallows, Slytherin is a stereotypical evil house. They weren't allowed in Dumbledore's Army, they were all supportive of the Dark Lord, they all hated Potter and Muggle-borns, they were all pureblood and persecuted those who weren't. But what about Larissa? Sorted into Slytherin the very same year Pott...
When the Golden Trio goes back to Hogwarts after much persuasion, and Percy, Annabeth, Nico, and Thalia go to Hogwarts for something similar to the Triwizard Tournament, there is bound to be trouble! Percabeth, Hermione/Ron- the rest are all single(ish- Ginny likes Harry).