He is a robot created by Dr. Eggman as the last and most powerful of the doctor's E-Series robots. However, he was deactivated and sealed in an abandoned base to guard Shadow the Hedgehog, who was in suspended animation in a stasis capsule. Furious at having his power wasted in this way, Omega swore revenge on his creator. 

Omega's only goals in life are to take revenge on Eggman for wasting his potential and destroy the doctor's other robots to prove himself superior. These two goals are absolute above all else in Omega's eyes. As a result, he tends to be extremely headstrong, reckless, aggressive, and destructive-and decimating anything that gets in his way.

https://www.youtube.com/watch?v=md5QPj3lLDY (Voice Reference)

If you're good at editing robot voices and sound cold and intimidating this part is for you.