User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-3481504-20120315211138/@comment-69.255.185.49-20120315220306

Death said he was on a leash of sorts, some how tied to Lucifer. That did not happen when Lucifer summoned him, since there is no evidence that summoning anything ties that entity to the summoner. So, perhaps the ring is what tied them together, if so, Lucifer created the rings.