"Well," Lucy answers slowly. "I'm not sure you should kill him." As much as she may hold a grudge against him, she doesn't think he'd deserve to die. "He saved the Earth, after all. It's just me he doesn't care about." Not to mention that a stake through the heart wouldn't work - they'd just regenerate. "Oh, and they've got two hearts." She points to each side of Peter's chest to illustrate.