Cenobite pets are created from the flesh of humans who were deemed not worthy enough to become true Cenobites. The ravages of time and the constant reconfiguration of flesh gradually turn these people into beings more animal than human... a living testimony to the true personification of guttural instinct and the desire to feed.
Cenobites can make their pets from just about anyone and anything; the people used can be living or dead, and sometimes things like nails, knives, chains, and so forth get tossed into the mix. More recently-made pets will sometimes have a slight recollection of their past life, but these are fleeting moments quickly superseded by mindless savagery - although certain pets have been shown to retain their ability to speak. Recently-made pets also typically will still have parts identifiable as human, whereas pets that have been "worked" on for several years will become utterly otherworldly creatures. Overall, the nature of a Cenobite pet depends entirely on the nature of the Cenobite that created them. Some Cenobites make intelligent companions and reward their pets for their loyalty, while others may create mindless beasts and simply see them as expendable playthings.