
The true identity of Joe Locke's 'Teen' was one of the big mysteries of the first half of Agatha All Along, and now that the season has come to an end, it's totally confirmed that he is indeed none other than Billy Kaplan/Maximoff AKA Wiccan, the son of the Scarlet Witch.
Beware, because we can't discuss this without getting into some spoilers for Agatha All Along, so turn back now if you're trying to go in totally unspoiled.