This is Theo Raeken

There's always that one person that brings out the worst in you. That was Theo for Stiles.
That darkness.

Stiles thought he'd seen the last of his brother when social services split them up after their parents died in a tragic house fire 10 years ago. Yet, here he was again. Here to darken Stiles' bright, hopeful life.

Stiles attempts to find out and stop his evil brother's plan. Playing Theo's little game to get to the truth.
But will Stiles keep playing until it's not a game anymore? Until the darkness consumes him?