A crutch. Trust me, you can learn to work without it for a number of things.

[He smiles back, crookedly, still finding it easy. Billy might be a little... mercurial, if he's being kind, but Loki is used to that, and smiles used to be somewhat rare. Enough so that he doesn't want to turn this one down, or the opportunity.]

...If that's what you'd like, we can. You were proving to be a reasonable pupil, at least by the end.