Animal Friend is a Fallout, Fallout 3, and Fallout: New Vegas perk. It does not appear in Fallout 2 nor Fallout Tactics. In Fallout, Animals will not attack one of their friends, unless the animal is threatened or attacked first. In Fallout 3 and Fallout: New Vegas, the second rank of the perk works the same. However, a second rank was also added. At the second rank, they will eventually come to your aid in combat, but never against another animal.