prey on

verb3

1. •
   To eat (as prey).

   • Owls prey on small mammals, such as mice.
2. •
   (figurative) To exploit or victimize.
3. •
   (figurative) To weigh heavily upon (a person's mind).

   • The past—to me, the dreadful past !—is one eternal present ; and the Promethean vulture of remorse preys on me now, and for ever. — 1852