Magnus laughs. "That's why Jack's my sword," he says. "Because Frey gave him up for Gerd, and Jack was like, 'no, I don't want no scrub, a scrub is a guy who can't get no love from me.' And then he was lost in the Charles River for, like, a thousand years until I pulled him out." This is also why Surt will use Jack to kill Frey during Ragnarok, if Magnus doesn't manage to stop it by keeping Jack well away from the Nine Worlds. "This is also now why Jack's motto is 'blades before babes,' I think."