forever trapped

The boy lived forever in a cave, trapped here forever. It was a underwater cave, except underwater was where it was.
His story is a tragic one, and too easily forgetable to tell. He had simply been swimming, when something caught his leg and pulled him under. He had passed out from exhaustion , and shortly after a mermaid had found him, and dragged him to his prison. The cave was at least 70 ft. down from the surface. Trying to escape would kill him, for trying to swim so high would be life-threatening.
So everyday the mermaid brought him things to eat. If they needed to be dry, she put them in bubbles.
So his life was spent here-boring and lonely. Now, was the mermaid evil?
He thought no, but that is up to you to decide.