Sergei is shrouded, both by the cloak he wears to disguise himself and in the mysteries of his past. All that can be guessed is, he comes from the Kievan Rus, a client state within the fractious Varangian Empire...most likely from the region of Pripyat.

He's dangerously capable with a rifle, and seems to be able to make it spit fire on a whim...

He roams the battlefield like a ghost. Saying nothing, doing nothing except exacting a terrible vengeance from afar.