Some people should not be allowed to open their mouths.
Chocolate Alchemy. I really do need to find some good non-abrasive chocolate. (Hershey bars are actually abrasive when licked.)

"Drinks for the House" Hermione/Draco (dubious consent, kink), Hermione/Harry (kink).
"Flame and Shadow" Ron/Pansy, and not so horribly fluffy.
"Seven Things That Didn't Happen On Valentine's Day At Hogwarts, Or Maybe They Did." by rageprufrock. Remus/Sirius, with extra James-makes-an-arse-of-himself and accidental potion-aided genderbending.
"Night-Blooming Heartsease" Snape/Neville, plot with character development & sequel, Final Battle with assorted character deaths.
"Severus Snape and the Ghostwritten Romance" A clever pastiche of Cyrano de Bergerac: Harry/Draco, Harry/Snape.

Fearsome things from fanfic (culled from the worst) -- the daily_sporfle
Pairings of Fear! -- theferrett