Dungeon Siege III

You get this achievement for becoming a "friend" of all of your teammates which is done by filling an ally's Influence bar about a quarter or so of the way up, possibly less. That means that you must earn 3 of the following 4 Deeds at some point during the game (not including the character you are playing as obviously):

Celestial Ally--Anjali
Bewitching Ally--Katarina
Academic Ally--Reinhart
Montbarron Ally--Lucas

You gain Influence just by playing with certain allies throughout the game and by making conversation choices with NPCs that your current ally likes (which is where the bulk of Influence comes from). You can simply play through the game and switch out allies until they each give you their respective deed or if you are like me and only ever played with one ally you can use the Maximum Charisma trick, which I'll detail here to save time.

At the finale of the game you will find yourself back at the original Legion Chapterhouse that is located on Pilgrim Road. At the bottom of the Chapterhouse is a room with a save point and two doors that lead to the East Forest outside (and the end sequence of the game). Save your game and walk up to the door and press RB to open it, but go no further. Your ally will then spat some prattle about serving with you, which will then be followed by an "Influence Gained" text at the bottom of the screen. Save your game again and then reload that same save. Walk up to the still opened door and press RB again when given the prompt. The doors will "open" again and your ally will repeat themselves along with giving you Influence once more. Repeat this process until you have enough Influence with all 3 allies. Shouldn't take more than a few minutes.