Guardian - опекун
Крёстный - godfather.

Это разговор с Фаджем

“Er—Minister? Can I ask you something?”

“Certainly,” said Fudge with a smile.

“Well, third years at Hogwarts are allowed to visit Hogsmeade, but my aunt and uncle didn’t sign the permission form. D’you think you could—?”

Fudge was looking uncomfortable.

“Ah,” he said. “No, no, I’m very sorry, Harry, but as I’m not your parent or guardian—”