It is the start of their Seventh Year, the Dark Lord is dead, and the only commotion the Golden Trio expects is to have boring, mundane lives from here on out. The Ministry of Magic has other plans. Enter Marriage Law and Dramione.
Draco and Hermione have separate lives for 6 years after the war. They live alone. Ron died instead of Fred. Now Draco is hurt while playing Quidditch and needs a blood transfusion. No one matches his blood type at that time except Healer Hermione. So she gives her blood and now, Draco remembers things he shouldn't.