Domion was a former player-character (Chris), same player as Sethius Soulcrusher.
The last Domion sighting was during the climactic Eru war as Donblas and Alastor "fought" on the battlefield. Domion was on the Eru side, and was particularly devastating, melded into the earth. He'd rise up behind and underneath folks, backstabbing with this nasty diamond grit-blade that ate through stoneskins. Paraswarm, with X-ray vision running, was the only one in the group who could see him coming, and he was killing allies right and left. There was no one else to do it, so Paraswarm confronted him, making an effort to match his movements and intervene whenever he rose up. They squared off for the dramatic fight... and neither of them could hit the other! It was comical, with both mighty characters uselessly swinging at each other! Domion sunk back into the earth, and descended beyond the 40 feet Paraswarm could detect, as the battle started going south for the Eru bunch. The players have not seen nor heard from him since.
The last Domion bit before that was when he put on a helm of alignment reversal, and became chaotic good. He got drummed out of the Assassin's Guild, and was quite bitter over it, muttering that he'd lost his edge. Also, he had been raised from the dead so many times he was down to about a 4 constitution, and those two things prompted Chris to switch to playing Sethius, who ended up running afoul of the law in Attelaria, insect-plaguing villages to make a point and getting put on the country's 'most wanted' list.
Domion became a major player in the Thieves Guild in Aertael, reportedly being the guild master for a short period.