While I Was Fearing It, It Came (джен)

Snape rolled his eyes. "You're not scared of blood, Potter. For one, you're a Gryffindor. For another, you seem to face down the Dark Lord with alarming regularity. If you were afraid of blood, you wouldn't have made it past your first year in this castle."
"What do you want me to say?" Harry shouted, suddenly filled with the same irrational anger that'd been so hard to shake since Cedric's death. He jumped to his feet, unable to sit any longer. "What would you have me do? I couldn't make myself break skin, okay? Is that so hard to believe?"
--
Or: a potion requires blood as an ingredient. Harry's afraid of a relapse. Snape just wants to know why Harry Vanished a perfectly decent brew. They come to an understanding.