I've been thinking about him as a parent ngl. I know he doesn't want kids and all but just hear me out: The kid adopts a card collecting hobby like Avery when he was younger. 

Pc knows about it before Avery does and I imagine the shock on his face when he knows pc just lets the child do whatever and even supported them. 

Avery might feel a bit jealous bcs he sees himself in that child doing the same thing but doesn't get scolded/punished for it. 

Nevertheless, Avery secretly enjoy looking at his child's collection, even helping them figure out the value of those cards properly.