Animal Friend

Animal Friend is a Fallout and Fallout 3 Perk.

Fallout
Animals will not attack one of their friends, unless the animal is threatened or attacked first. Exactly what an animal is in this world is open to debate.

Fallout 3
At the first rank of this perk, animals simply won’t attack. At the second rank, they will eventually come to your aid in combat, but never against another animal. This perk affects only the Dog, Yao Guai, Raider Guard Dog, Mole Rat, and Brahmin; creatures like Radscorpions, Centaurs, Mirelurks, and Deathclaws are unaffected.

This is one of the best "standard of living" perks, as not having to deal with the duo's of Yao Guai is very beneficial as is not being given away by Talon Co. or Raider Guard dogs.

Additional Dialog

 * Tree Father Birch in Oasis explains why animals are in oasis. There appears to be no benefits.

Bugs
If you remove the perk via the console, animals may behave as if you still have the perk.