Ive got a theoryraco will give Hermione a love potion so she will become obsessed with him and do anything for him and he asks her to kill Harry or lure him into a trap.
ORame thing but Harry tries to attack Draco for some reason and Hermione protects him and goes O.T.T. and accidently tries to kill Harry.
Then at the end of either Hermione realises whats happened or comes out of the love potions power and goes into a nervous breakdown.

I know it probably wont happen but i think its a really exciting plot.