In what ways does he show that he resents losing power over Huck almost as much as he resents the loss of Huck's money?

Pap had never had a relationship with his son. Pap was a pathetic drunk who left his son to fend for himself. When Pap returns, he finds that Huck has not only come into money but is a minor celebrity as well. Control over his son gives Pap a shred of purpose. He uses his son to give meaning to his meaningless life. Pap basically has to kidnap his own son and lock him up as if Huck was a possession he could keep for himself. Of course Huck, who treasured his freedom above all, would have no part of Pap.