Loner

Loner is a Fallout Tactics Perk. So far it hasn't appeared in any other game.

Your solitary childhood and upbringing mean that you work much better when alone. Get +10% to all rolls when outside the influence of other squad members.
 * Notes: It is possible to gain this Perk as well as Team Player if a character has exactly 4 Charisma, in Fallout Tactics. Each Perks' descriptive text contradicts the other, but the bonuses apparently stack.

Bugs
The bonus is always active, no matter if there's a squad member close by or not.