Barbarus - The Coming of Mortarion: After the Emperor of Mankind's 20 Primarchs were scattered across the galaxy from Terra through the Warp still in their gestation capsules by the actions of the Chaos Gods, they came to rest on many different human-inhabited colony worlds. The Stygian Scrolls record the fate of one of these Primarchs, Mortarion:"There was one who came to rest on a bleak moor, strewn with the dead and scattered with the carnage of battle for leagues in every direction. This was the world of Barbarus. A planet perpetually shrouded in poisonous fog, whose mountainous crags were ruled by warlords with fantastic powers and horrific appetites, and whose human settlers, stranded there millennia before, were crowded into the lowest valleys, beneath the choking mists. They lived lives of unrelenting terror, eking out a peasant's existence by day beneath a dim sun which never burned completely through the fog, and cowering by firelight after dark from the terrible beings which moved unseen above."The greatest of these overlords stood in triumph on the battlefield, reveling in his massacre until the silence was shattered by a child's cry. Legend tells that the warlord walked the sea of corpses for a day and a night in his creaking battle armour, drawn by the wail of the infant. For an instant, he considered ending its young life; but no mere human ought to be able to breathe the poisonous miasma of the heights of Barbarus, much less cry out as this child did.For long moments he contemplated this thing which appeared to be human but was clearly much more; then he gathered up the infant and carried him from the carnage. For all his dark power, until that moment he had not had what this child now promised: a son and heir. Born of death, upon a field of death, the warlord christened the infant Mortarion: the child of death.When Mortarion was taken by the overlord, his master tested the infant's limits. When he had determined precisely how high into the toxic clouds of Barbarus's peaks the child could survive, he erected a stony keep and fenced it behind black iron. Then he moved his own manse beyond, to the highest crag, where the atmosphere was deadly even to the nascent Primarch.Mortarion grew to adolescence in such a world, of citadels of weeping grey stone and cast-iron fences, where the very air was death, and the sun never more than a distant smudge. It was a world of constant war, against opposing lords who came with golem armies of stitched-together dead one day, then tormented shapeshifters, more monsters than men, the next.The Primarch was shaped by his grim environs, but he was a child of the Emperor for all that - superhumanly resilient to the poisonous air around him and superhumanly strong even in the absence of sufficient sunlight or nourishment. Mortarion possessed an intellect which was highly keen and which asked questions his lord was not wont to answer.Increasingly, the questions centred around the fragile things in the valleys below, which the warlords preyed upon for their corpses to reanimate, or victims to accurse. His master kept Mortarion as distant from the human settlements as he could, but his very act of denial fed the maturing Primarch's obsession. The day finally came when Mortarion would be denied no longer. Mortarion slipped through the dungeons from his keep.The last thing he heard was the voice of the overlord, the only father he had known, roaring in the miasmic darkness from the high battlements as Mortarion descended from the mountain, renouncing the Primarch for his betrayal, warning Mortarion that to return would mean death.