"I didn't take anything from you! I was trying to save your life!" Both paths led to the same place. Giving Harry his blood might have done the same that the serum had - but look at that, Harry had taken the serum anyway. And, as always, it was Peter's fault. "You're not thinking straight, man - !"

Peter yanked on the web, pulling them back up, intent on getting them to a rooftop. To talk or exchange blows, Peter didn't know which. Harry's blade stopped that, however, severing their connection again. At least he'd gotten him away from the damn glider, for now.