To be honest, when Gio had sent out his challenged through the billboard. He had really just been working on hope.
He had been hoping that Celeste would see the message. Hoping that she would not dismiss it and go about her way. Even more than that, he had been hoping that not only would she see the message. That she would understand what it meant and respond accordingly.
Uncle Rex had died before he could teach her the ways of the family. And even if he had taught her, she would have been too young and would have forgotten either way.
But her mother had been part of the family, and a member of the bloodiest sect. The one that handled issues that could not be dealt with through words alone. Surely she would have taught her daughter something.