His name was, not important. To a demon beast, names held no meaning, only strength mattered. One only used their name for their parents, and their parents alone. But his were long gone.
The demon beasts naturally held little to no intelligence, as in the depths of the abyss, where the corruption of darkness had long since withered any semblance of wisdom from any life's mind, all beings moved on instinct alone. He was no different.
From the moment he was borne, he fought everyday. The first day, he fought his brothers and sisters for the minuscule resources that existed in the abyss, and alone survived. On the second day, he had to ambush the beasts that approached his parents' nest, and held their necks until his parents arrived, he lost a leg in the process. It grew back with enough blood drunk. On the third day, his parents were killed and eaten, he hid in their corpse to ambush and slay their killer. He ate all their corpses. Every scrap of meat was precious in the abyss.
Like this, he grew stronger, slayed and devoured stronger opponents, left offspring, and lived a long life. A life long enough until he was older than most of the others. This was not a considerable feat considering the average lifespan of a demon beast was under a dozen years. The stronger ones lived to be thousands of years old, he was still far from them.
In a thousand years, he gained the strength to wander unmatched for thousands of miles. Only the elder Abyssals had the right to challenge him.
But to him, it wasn't enough, he lived in the throes of battle. When he no longer needed it, his indomitable will to survive gradually declined. To the strong, the only pleasure is a worthy opponent, where death is at every turn.
It is ironic, the weak seek battle to live, while the strong seek battle to die.
Yet how, despite being an everlasting tyrant in a land of cruel darkness, did he end up the contract beast of a little girl?!