The Sea Maiden is as much the villain as the fisherman. They both made a deal about someone else's life.

The thing is, my parents promised me to things and used me in a bargain. They had no right, and today as an adult I can and did run away.

Vows made about me by someone else without consent on my part are void. My mother was as bad or worse as my father.

My opinion is your mom doesn't get a pass because she "didn't have a choice." She had choices, they were hard and she refused to make them. Doesn't mean she didn't have them.

But yeah, the two original characters are both villians and the son had the right to escape because he didn't make the bargain and only he could.

Some great thoughts and things worth thinking about. But there are definitely two villains here.