Sanguinius

Winged, luminous, and beloved beyond any of his brothers, Sanguinius was the primarch the Emperor's other sons trusted without envy and the Imperium's mortal armies wept to behold. He was raised upon the blighted moon of Baal, where the tribes named him angel and he made himself worthy of the word, uniting a poisoned world before the Emperor ever came to claim him. Alone among the primarchs he carried the gift and curse of foresight, and alone he bore the shadow that haunted his gene-seed, the twin flaws of a rage-blind Thirst and a doom he glimpsed but never fully spoke aloud.

In the Heresy, Horus reserved for Sanguinius a cruelty fitted to a brother he could not turn: the trap of the Signus Cluster, where the Blood Angels were lured from the road to Terra and cast into a daemonic snare meant to damn them body and soul. Sanguinius held his Legion back from the abyss by the sheer force of his will, broke the daemonic host arrayed against him, and led his blood-marked sons out of the warp's grasp. He came late to the Siege of Terra, and there, upon the walls, the Angel would meet the ending he had long foreseen, buying the Imperium its survival with his life.