Jack and Jill(ian) seem to be long acquainted with each other. Jillian indicates that she believed he had a crush on her. Jillian on her part seems at least fond of Jack and considers him to be a genius Foolamancer. When the two met in battle both seemed to be deeply affected; seeing Jillian and hearing her speak his name appears to have largely cured Jack of his insanity. Jillian has offered to accept Jack to her side both times they have encountered each other within the comic, and although both times Jack declined the offer, he has also expressed some regret (to himself) in not joining her and implies that he may yet switch allegiances if she continues to ask in the future.