@explosivebullet
My mans, I have a few ideas to make it have a bit more backstory for Sergei, and a little for Kyle.
For Kyle
Around the time he was thinking of joining the NBC, he saw Dylan. He saw Dylan as inspiration. Due to this, he used his helmet to make a helmet for himself.

Sergei,
At around 21, he joined a highly vicious army-like gang. Knowing Sergei, he overthrew it, and around 2 years later, he blew it all up. Then he FORCED the leader of Bolako to let him be on the team. This time – he didn’t blow it up to years later. He stayed loyal. He became one of their biggest soldiers.