Well, of course, Snape tried it-if he’d got as far as this house, he’d have met a fully grown werewolf-but your
father, who’d heard what Sirius had done, went after Snape and pulled him back, at great risk to his life… Snape glimpsed me, though, at the end of the tunnel. He was forbidden to tell anybody by Dumbledore, but from that time on he knew
what I was…”

Chapter 18