He was originally a Grunt before gaining dark powers and being possessed by the Demon.
He was originally a grunt named August Huffman who was imprisoned due to mental issues. He was later found by Zalmamder Oox and incorporated into Project Nexus, as well as renamed to "Yeelon Mekyr" and put inside a tube.
REALM: Project 00X
However, Yeelon caused an explosion that freed him and his fellow test subject Kelzad from their tanks. The two then teamed up to escape.
The two fought their way through several 1337 Agents and A.T.P. Engineers before briefly splitting up. When they reunited, Yeelon was much darker. The two made their way to a balcony and, from afar, they witnessted The Auditor's defeat at the hands of Hank J. Wimbleton and Sanford.
They then made their way back into the building via a ramp, though the landing injured Yeelon's back. Kelzad and Yeelon were then confronted by Zalmamder, who offered his hand to them. However, Yeelon began to shake violently and cut off part of Kelzad's head before flying away. He then gained red eyes and a mouth and was renamed Sokar.
REALM: Project M3KYR
Sokar later attacked the Science Tower around time of Kelzad's second escape attempt. He possessed several A.A.H.W. grunts and had them attack Kelzad, eventually confronting Kelzad himself on one of the higher floors.
Kelzad jumped at him and knocked both of them off the building, however, Sokar transformed into the Demon to avoid taking damage and grabbed Kelzad. Just then, Zalmamder and his soldiers appeared and shot at Sokar, forcing him to drop Kelzad and retreat.
Sokar later revived an army Agents, Engineers and Abominations and sent them to attack the Science Tower. Sokar transformed into his Demon form, flew up to the top of the tower, and broke off the Solarium from the rest of the building. Kelzad fought his way through Sokar's army and confronted him at the top of the building. Sokar used his powers to change the color of the sky from red to purple before summoning a scythe and preparing to attack Kelzad.