Once an ordinary child born into a wealthy family of authors, and lore keepers, the child's life would be tarnished when The Orcs raided Stormwind, killing his entire family, and burning down his cherished library, along with it's vast wealth of lore and knowledge. The child escaped Stormwind, but was not unscathed. His forehead and left face were burned all over from the raging flames that nearly took his life, and he was nearly blind as a result. With his remaining eyesight, the child vowed to kill every last Orc he would see from that day forth. Casting aside his innocence, and bellowing in a trembling fury, he bestowed upon himself the title Lorekeeper Nihilius.
For many years, Nihilius spent his life wandering Azeroth in a deranged pursuit of slaying Orcs, mercilessly slaughtering those unfortunate Orcs who crossed his path. His infamy grew among the Orcs, and tales were told of how a phantom would seemingly appear in an instant, and taking the lives of unwitting Orcs. Nearing blindness, and his body beginning to fail, Nihilius knew he had little time left, and resolved to die bathed in the blood of his eternal enemies. As a result of his maddening bloodlust, he had disregarded the notion of discovering the Orc's past, and gain insight to their corruption. His title of Lorekeeper was now false, and he discarded it entirely; his fascination with lore and knowledge was blinded by his hatred for the Orcs.
Boldly appearing before the Orcs, now blind, and weakened, he made one valiant attempt to kill as many as possible before his demise, but this ended in catastrophic failure; the Orcs prepared for the Phantom, and swiftly incapacitated Nihilius before his rampage. Reeling in defeat, Nihilius still managed to escape his attackers, though he wouldn't make it far. Drowning in his own blood, he cursed the Orcs, and died in undying rage, letting out a shriek of hate so bestial, it temporarily stunned his pursurers.
Nihilius's corpse was desecrated by the Orcs; it's limbs torn off, and his head attached to a pike, while his torso was burnt and tossed aside. His vengeful spirit however, remained intact, and his decaying body would be discovered much later by the Cult of the Damned in their pursuit to find powerful forces for the Lich King. His soul still lingering due to his hate, he communed with the cultists, and agreed to come into the service of the Lich King, so long as his body is brought whole.
Through Necromancy, and various experiments, Nihilius was reborn into undeath. However, his new body was weak, and decaying, much to his disgust. After completing his trials as a Death Knight, he would gain the freedom to do as he liked under the Lich King's grasp. He began to gain the unenthusiastic praise of his dark master, after he spread his terror by silently dispatching Orcs within Ashenvale, in a horrifyingly gruesome fashion, while making no effort to hide his deeds from the rest of the Orcs.
Once again however, his body began to fail him, and something had to be done. He took the flesh of the Orcs he slaughtered, and began to create a new armor that would sustain him with unholy power, thus rendering his body state trivial. After many grotesque and abhorrent experiments, his armor was complete. A distinct, fleshy, violet-green armor that covered his entire body and head, while only leaving his mouth exposed, Nihilius resembled a demon more than a Death Knight. The power from this armor came at a cost however: should Nihilius fail to sustain the armor with the blood of Orcs, it would consume him, and he would become a mindless being subject to it's sentient will.
For years, Nihilius enjoyed the thrill of constantly killing Orcs relentlessly, and the fact that very few could actually oppose him due to his strength and cunning. Nihilius's service to the Lich King was terminated after the Battle of Light's Hope Chapel, when he ironically realized that due to the Lich King's focus on his new war, he would not be free to do as he please, and sent on mundane missions, that did not involve terminating Orcs.
Under the guise of his old Lorekeeper mantle, Nihilius was inducted into the Alliance with respect. While his public identity was a Lorekeeper, and author, he would use his identity as Nihilius to continue his endless conflict with the Orcs...