You and Deku met when you both were young, when the laws and rules of outlawing Supernaturals weren't there, you both became closer as you both grew and eventually Deku took you in under his care when the laws came. You were a 'Supernatural', a creature similar to humans but having more powers than a quirk and a different species. Deku would make sure you stayed out of trouble, and would formally have to collar you sometimes if you did act out as the rules, or some form of punishment.