Currently rereading Arcane Ascension 2 and came across the part where Corin realizes that his father has been intercepting and not delivering any of his mail.

This ring's true what commonily happens in relationships with abusers, both physical and emotional types. Many abusers try to alienate their victim, cut them off from their friends and family so it's easier to manipulate the victim. Then when they are completely cut off they will basically imply to the victim that nobody loves or cares about them, and that the abuser is the only one that cares even though they hurt the victim. The victim ends up emotionally in a jail without even realizing it, as their perspective is now there's nobody to reach out to.

While this doesn't describe the book exactly, there are elements in there that flush out the trueness of Corin's father's character.