Raging across the lower planes since the beginning of time, the blood war pits the fiends against each other in an eternal battle for dominion over the lower planes. Currently the opposing factions involved where the chaotic and individulaistic tanar'ri and the organised and lawful baatezu, the Yugoloths the strangest and most enigmatic of the fiends maneovering between them trying to keep the balance of evil or something. With the Yugoloths you never know.
In the Abyss, far away from the battles of anyone but the tanar'ri fighting for larger scraps of the infernal plane the lord Graz'zt, one of the oldest and most powerful fiends raged. His favorite pleasure slave had died giving birth to his son. You don't really want to know, what atrocities a seriously angered fiend of his power is capable of commiting, so it will stay a dark in two ways. One from the prime slang for something evil, second for the planar word talking about something kept secret.
For some reason he allowed Tra'citz to live and the cambion grew into adolescence. Even though Graz'zt couldn't care less for the Blood War, he sent his wayward son there, already in command of a small group of fiends, lousy least tanar'ri at that, but still a command. As a powerful warrior born of an abyssal lord and a paladin capable of defeating a marilith in single combat he was successful and quickly his unit changed into one of crack troops, trusting him. That is he could turn his back on them for more then a heartbeat without fearing to be backstabbed. His reflexes and their fear of his power kept them in line for the time being.
After he couldn't get rid of his son this way, Graz'zt assigned his unit as part of his personal guard. The guard was allowed to be closer to the fiendish prince than anyone else, which was a blessing and a curse at the same time. Tra'citz lost many of his unit to his father's rage and learned about his origins when he managed to observe one of his father's rants. Even though relatively coherent as tanar'ri go, even he needed an outlet for the pressure and unstability that is part of every tanar'ric personality.
At this point the young cambion started to hate tanar'ri even more than fiends (or half-fiends) hate everything. Whenever his duties allowed him breaks, he assassinated high-up tanar'ri and soon became adept at doing so. No-one was really surprised, after all cambions were known to serve as blood war assassins, since their humanoid build made them more flexible than many other fiends, being restricted by their impressive array of natural weaponry in ways not directly obvious.
Tra'citz didn't walk through the shadows or sneak. Anyone trying to do so would have been noticed ten miles through dense mist by any of the more powerful tanar'ri. He was one with the shadows and the darkness. He was just another shadow, sometimes even more than only figuratively. A black dagger was in his hand and dove into the heart of a balor. The enchantened weapon pierced through the tough hide impervious to many attacks and easily and found its mark. The fiend didn't even have time to curse.
The dagger vanished and the Abyss was only filled with the constantly milling and aimlessly clawing manes and dretches. In Graz'zt's realm the shadow wasn't more visible than anywhere else. Tra'citz was an expert assassin of fiends, something few ever achieved. He managed to enter his father's domain unmolested and unnoticed. Using his skill and routine the black dagger stabbed another time, but this time it didn't graze the skin.
Strands of blackness deeper than the shadows slammed into him. They slammed him into a wall and slowly engulfed him like a cocoon that didn't allow him to move. Out of habit he stopped breathing in any confined space. He didn't need air. Graz'zt turned around, eyes burning with diabolic danger. They bored into his would-be assassin's face and stayed there for a long time. Even mountains with some sense would flee in terror, but Tra'citz didn't even blink. He had underestimated his quarry. Now he was at the fiends non-existent mercy. That was the way of the Abyss.
Still, sometimes even fiends knew fear...
The cambion was the subject of ever more excruciating turures far more painful than any mortal could endure, but a Blood War hardened fiend is nothing if not tough. None of the endless pain managed to break his spirit or bring him to reason, whatever a tanar'ri considered reason. The tanar'ri lord started to think about ways to increase the pain, some even going as far as hiring kockrachons to do the job. He would never do that, but he was running out of options.
Dissatisfied and angry, even his allies avoided his presence, because a tanar'ri in a foul mood was capable of doing anything as long as it was wicked, depraved and connected to incredible terror. Then one day wicked manical laughter echoed through all of his realm, making even his most powerful minions cower in fear. Finally he knew what to do to get rid of his son. (For some reason he could not kill him, even though he tried.)
The cambion ended up in the foul flood of the styx, washing away his memories, reducing the mind to that of an infant. Knots moved beneath the still dripping skin and bones cracked as they where violently reshaped by brutal fiendish magic. When the nerve-wracking transformation was done, there was a sterile female human child. With a wicked grin the fiend teleported it to the world of Aslaniar, where even fiends feared to tread. He had once been summoned to this place. It was a memory he would rather forget, but the waters of the Styx where never selective...
Smiling a wicked smile (do fiends ever do anything in a way that is not wicked? I don't think so), Graz'zt returned to his realm, anticipating what he would do to the female, once she was grown up and he found her. If she survived in the first place. How could a helpless infant girl survive in a world that was even lethal to him? Little did he know about the nature of mortals...
When a body remembers the circumstances of this cambions birth, she might know that he was blessed by his dying mother in the name of Lathander, one of the more powerful gods of good. The morninglord made sure, that the memories where not as completely gone as they where supposed to be, while Tymora, on whose luck his mother often subsisted worked her own will in a subtle way.
The girl was found by a caring soul in the snowy wastes of the world. Was it just a coincidence or the will of the gods?