Alan Wake

Right down the path after starting the night part of episode 2, you will find a hurt Rusty who will ask you to turn on the lights from the house across from where he is and get you both to safety. As you run for the lights and find out you have been sabotaged you'll hear a loud noise and as turns out, Rusty gets taken over. Go outside from where his body was (you'll see a big blood mark on the window) and he'll attack you in the back yard. Make sure you take down his Dark Shield and then pump away at his head, be weary though, he takes a little more lead than your average Taken.

Story related. After finding Rusty hurt inside the damaged park visitors center, he'll end up as one of the taken. Kill him for the achievement.