Cosmo Jr.

Cosmo Jr. ( コスモ,  Cosmo Junia) or otherwise known as the Living Doll ( 住雛  , Juuhina ? ), is the pet of both the Mafia Pirates and Cosmo D. Cheshire. The doll was the childhood favored play thing of Cosmo, then finding a strange devil fruit and after having his doll “eat” the fruit it came alive. Since then the doll has been able to interact with Cosmo and the other members of the crews, also the doll is considered to be the second creepiest member of the mafia pirates, after Cosmo himself.

Devil Fruit
Cosmo Jr. has "eaten" a currently known Paramecia-type Devil Fruit, in which the doll is able to walk and talk like that of a normal human. It was confirmed that it was not a zoan type devil fruit, because Cosmo had commented that his doll feels no pain or has no feelings. But rather it is animated to move, walk and talk. It is believed that this is all that the devil fruit can do, most of the Mafia pirates assumed that it was a devil fruit that animated the doll. But the doll does suffer the standard weakness of the devil fruit, because Cosmo stated that if his doll falls into the ocean. It will just go back to being a normal doll, thus losing its abilities to walk, talk and such.