[@EchoicChamber]

Yep! The link is there. Maybe, their families know each other by name or have fought each other at some point. Fis' family, unknown to him, are Warlock's for hire. Well, they started as that. They knew they had magic, the knew they were good at it and they used it to rise in the world. They succeeded, for the most part. One of them knew there was a need for more, and so that ancestor created the relic that would come to bind its first demon, permanently. They grew stronger and because of that, Esp's and Fis' families might have met due to their infamy and power. Plus, the Kalix family are closely tied with demons and Esp's family can temporarily bind demons. Might have exchanged tips to improve their magic, or something. :D