Fluffy

 are two Radroaches in the Abandoned Shack where you can get the Victory Rifle. They are caged in, but you can open the cage. They will be hostile to the player, sadly. If you want to keep them alive in the cage don’t go in with Fawkes,as he will kill them. Additionally, Dogmeat can kill them as well. If you get too close to the cage, they can still attack you and give you damage.