But you DO have my consent! Evil Laughter

Harry Potter, when transported to the graveyard for a freaky ritual, has quite possibly the dumbest idea in his life. Wormtail's chant says that his blood must be 'forcibly taken! So he'll just give it willingly! Potions have been messed up on less, one time Ron messed up Malfoy's potion by glaring at it with seething hatred. Consent is king after all!