Trueblood Vampire
Humble and friendly to demons, although he has a superiority complex when around vampires. A little cautious around humans but generally able to trust them to some degree. He is highly unforgiving to any who seek to sow hostility among demons and humans, regardless of who they are. Will fight and risk himself to protect those whom he has come to view as friends.
Silversteel Spear - "Silversteel" is an metal with magical properties, developed by the ancient vampires and is incredibly rare. It has the ability to cut through/channel/store magic in itself, and and breaks or cracks in the metal are immediately "regenerated" automatically. Atreus' Silversteel Lance is able to break off a part of a tip in the body of the enemy and "regenerate" the point so it is usable. The point cannot be removed physically, requiring powerful magic to be able to remove or by Atreus' will. Any attempts to remove it by force will cause the tip to move deeper in the opponent's flesh.
Atreus is one of the last remaining "Truebloods", the original vampires. As one of the patriarchs of vampires, Atreus' vampiric abilities and powers are all undiluted by millions of years of evolution and adaptation. While his sense of sight suffers in sunlight, he isn't harmed by it. He regarded as royalty by most vampires, treated as a god by some others, yet he has no love for any of them, despising their way of life, being chained by greed, lust and gluttony.
He has lived so long his age is no longer a concern, and his fighting skills have been honed by millenia of battles, either as a demon, or posed as a human in one of their wars. He takes it upon himself to go into the human world and take action for the greater good, either preventing humans from coming under the oppression of tyranny by one of their kind, like in World War II, or to prevent those whom desire to expose the demon world and start another witchhunt for his kind.
He has seen the human world grow and advance in their technology, but little in their wisdom, although he bears no hatred, for he realizes that fear is a powerful and overwhelming emotion, one that mankind has not yet managed to control. Yet he sees hope that humanity might be able to coexist alongside demonkind, and thus respects their rightful place in the world and does not seek to conquer them, but rather to live peacefully alongside them. Though he has no defined plan or action for such a hope, he is willing to fight for it, whether through force or by negotiation, and will show no mercy to those who stand in his way.