There is a prominent foster care character in Mr Mercedes (2017, Netflix).

Lou Linklatter (Breeda Wool) is a computer nerd and co-worker/friend of mass murderer, Brady Hartsfield. What the 2 have in common, apart from their intelligence and tech skills, are difficult childhoods and social alienation.

At first the series seems to be suggesting that being in the foster care system doesn't mean you end up like the pyschopath who wasn't.

By the end of the show, however, we're back on familiar terrain with the hint that Lou is becoming exactly like Brady.