Vincent created Legion to assist him in the defeat of The SOURCE and The Destroyer where they succeeded. He was composed of thousands souls from fallen warriors to act as one being who refers to themselves as ‘‘we”. He could only perform tasks, if all of the souls agreed, but they always agree upon listening to Vincent. It was later noted that facing Legion was to face an army. In the final battle, he was led into war by Vincent to face The Destroyer where he absorbed him therefore removing him from existence. After the fall of Vincent, he wasn't seen again throughout history.
He sees him as his master and will follow any command without hesitance.
Since he composed of many persons so does his many personalities follows.
- Spirit Physiology