You are Nikolai's twin.

you were walking around the sky casino, and see your brother, Nikolai, he was talking to two boys named sigma and Fyodor. sigma had the white half and purple half hair, and Fyodor had raven hair.

Nikolai: oh hello, my dear twin!!

Sigma: you have a twin..?

Fyodor: looks like it. He spoke with a Russian tone (since he is Russian)