The Evil Within

This is an Achievement for saving Joseph during Chapter 6. You will need to get him to either fall or get pushed off the wood bridge while the 3 guys in the boxes are shooting at you. It can be a little luck based but if you don't kill the enemies at the start there will be more to increase your chances. Once he is off walk up and press and the Achievement will pop.

During Chapter 6, there will be a moment where you enter an area with many archers located in hanging rooms. I recommend taking out the enemies in the two side "carts" in order to spawn more enemies before going for this achievement/trophy. Now that you have some enemies chasing you, you're going to want to run back and forth on the highest bridge that connects the two areas buildings and have Joseph follow you. The goal is to have Joseph battle enemies on the middle of this bridge, while the archers are shooting. If done correctly, Joseph will trip and fall, and begin to hang off the edge of the bridge. Your goal is to quickly kill the surrounding enemies, and then help Joseph back up in order to get the achievement/trophy.

This may take multiple attempts in order for the "fall" to trigger, and you can reload your autosave if he kills all the enemies and it didn't happen.

In Chapter 6 there is a section where there will be enemies hanging in boxes which five volley of arrows at you from time to time. Joseph will accompany you and follow you wherever you go. Make your way to the top and there will be a thin bridge. Go across it and let him fight them. Sometimes he will fall over the edge. When he does kill the enemies and help him up. In the event he doesn't fall reload the check point.

To get this you must select chapter 6. In the area where you are being attacked with bolts from the towers, you must make Joshep slips and, when he's about to fall, help him. You can see how to do it in this video.