"Sernutarzi" may be a fictional or mythological name created by its author for the devil's son character. There is no established reason or origin for why this specific name was chosen for the character. It could simply be a creative decision made by the creator of the story.
no the devil does not have a son he gained the power that he has by getting others to think that they can be better and more powerful that God, and so the devil had turned away from God and turned others away from God, and is still getting the pleasure. i say "stop the devil" and "worship God " the creature of all things. (read the bible or try go to church. PS: God loves you! The above answer is obviously from someone who is Christian themselves, and an accurate reflection of his belief system. For a more secular answer, I'd say: None of the major western religions depict the devil as having a son, but many of them (most famously most branches of Christianity) do cite the appearance of the son of the devil as being one of the events of the Apocalypse.