Intended to be one of the Sin'shosts, Fluffy was accidentally awakened earlier and wound up wandering into the Virtue's realm. Content would up taking him in as a pet, giving him the name of Fluffy. He spent an period of time during various chores and things around there while the Virtues debated on what to do with him. Eventually, he got too overwhelmed by Content's attention and got Sharing to warp him back home.
Fluffy was originally intended to aid the Sins in combating the force of Death, but Chastity was forced to take that role.
(we would add more but that would be spoiler to newcommers)