Talion was a Gondorian Ranger, one of the last remnants of the Gondorian garrison which had guarden the Black Gate. While most records remember him as deceased, this ranger has a tremendous legend attached to him. According to it, Talion was separated from his family in youth by Sauron the Deceiver. Talion was later wouned by a Morgûl-blade and would have become a wraith under the Nazgûls domination, but his dying body eventually became possessed by the tortured soul of Celebrimbor who, ridden by guilt and his torture by Sauron, had become a wayward spirit, finally loosed from his bounds. In a long turn of events, Talion/Celebrimbor fused into one body and began to craft another ring of power to stand against Sauron himself. In the end however Talion just became a rival Warlord, leading his army of rogue Orcs and becoming more and more corrupted by the growing influence of his ring. As Celebrimbor's soul got caught in a never-ending struggle with Sauron's spirit, Talion finally fell and did indeed turn into an evil Wraith under the command of the Nazgûl.
The existence of a Character like Talion/Celebrimbor , a "Half-Wraith" is in serious conflict with J.R.R. Tolkien's cosmology.While in theory elven spirits could refuse to go to Mandos and become wayward Poltergeists, the souls of men were destined to go to mandos and after some time to travel further to the timeless halls and illuvatar and could not willingly refuse to do so.However a souls strife to the west could be delayed for some time, for example by use of a very powerful magic artifact or a very strong unfullfilled oath or a mighty curse.Anyways , even if a dying body, it's soul bound to the matter of Arda by a magical anchor, was possessed by a second, more powerful soul, it would not have had the abilities of Talion, and even if these would have come from Celebrimbor's greater powers and if some of Talion's memory had remained in his body (like the Hobbits who, after having been possessed by barrow-wights had gained some short glimpses of memories of men who fell in war with Angmar), the domination of Orcs via magic powers would have been considered evil sorcery and Talion's Soul would inevidently have fallen and become corrupted.