Curtis is a snake reptiles (especially snakes according to the story) are cold blooded and abusive and only care for one thing and that is their mates. Curtis behaving like a "father" is just him being nice to quinquin he could give 0 f^cks about them that includes quinquin child.. the only people who understand her is tiger and park maybe even the mermaid. Regardless the reason little snake is acting the way he is because I am guessing he is now in adult hood meaning that he carries his father memories in a way he is half of him and doesn't really see his mother as a mother which is why Curtis warned her about the little snakes. (I still don't like Curtis by the way I've been telling this to everyone that he is a-hole but not to quinquin but still doesn't respect her in general)