After Orion was framed, Omicron hunted down the men involved with it, and became notorious and the same time. He learned how it was Maw and relayed it to the police, but Maw came and injured Omicron. After Maw died, it was peace, until he revived. Omicron wanted to get him, but Omearc and Arya stopped him. It was Omicron who trained Omega in the ways of the assassin.
Sorry the hood looks weird. Music: https://www.youtube.com/watch?v=qk4gV4amO9I&list=PLpXnJosOQVEuetP68xZxROFhyMDKaeLiv&index=11&t=0s
