Horus "Little Horus" Aximand was the Captain of the 5th Company of the Luna Wolves and later the Sons of Horus Space Marine Legion during the final days of the Great Crusade and the Horus Heresy in the early 31st Millennium. He was a native of the Luna Wolves' homeworld of Cthonia. Aximand was often called "Little Horus" for his remarkable physical resemblance to his Primarch Horus, which was a common physical characteristic of those Space Marines who bore the gene-seed organs of the Warmaster. Little Horus was one of the four members of the Luna Wolves' Mournival, the informal advisory council for the Legion composed of the four company captains who were deemed to possess personality traits and experiences that best complemented the Warmaster's command over the Legion and the Great Crusade itself. Little Horus was a member and a strong supporter of the informal warrior lodge that was founded amidst the Luna Wolves and several other Astartes Legions during the Great Crusade after the practice was adopted from the primitive tribes of the Feral World of Davin. This warrior lodge ultimately proved to be one of the channels through which the corruption of Chaos ultimately transformed the Sons of Horus into a Traitor Legion of Chaos Space Marines.
Horus was wounded in battle against the Nurgleite Eugen Temba by the Chaotic relic blade known as the Kinebrach Anathame on the moon of Davin after the Luna Wolves returned to that Chaos-infected planet. Little Horus backed his fellow Mournival member First Captain Ezekyle Abaddon in his determination to deliver the dying Horus into the hands of the Chaos Sorcerers of the Davinite Temple of the Serpent Lodge, a Chaos Cult, after the Word Bearers' First Chaplain Erebus had explained that the priests of the Serpent Lodge might be able to help Horus recover. When Horus was corrupted by Chaos during his "healing" and began to bring the rest of his Legion into the service of the Ruinous Powers in his quest to overthrow his father as the ruler of the galaxy, Little Horus sided with his namesake and Abaddon against his fellow Mournival members Tarik Torgaddon and Garviel Loken who remained Loyalist servants of the Emperor of Mankind, breaking their fellowship. As such, Little Horus willingly turned Traitor and joined in the Traitor Legions' assault on their Loyalist brethren during the Battle of Istvaan III.
During the final assault against the Loyalist holdouts on Istvaan III, Little Horus defeated and slew Tarik Torgaddon in single combat in the blasted ruins of that planet's former capital, the Choral City. Horus Aximand also participated in the Drop Site Massacre on the world of Istvaan V, fighting alongside his fellow Sons of Horus Astartes and dominating the battlefield besides Ezekyle Abaddon. Unlike Abaddon, who embraced Chaos willingly, finding it only further empowered a nature that had always been prone to choler, violence and attempts at dominance, Horus Aximand found it more difficult to betray his comrades and the Emperor, but comforted himself by placing all of his faith in the rightness of the Warmaster's actions, who had never failed him before. Yet the death of his Mournival brothers deeply marked Little Horus, and his actions on Istvaan V were characterised by a mechanical, emotionless quality that was quite at odds with his once jovial personality. This behaviour indicated that he had been forced to bury his doubts about the Warmaster and his Legion's actions deep and his own personality even deeper, perhaps in a place from which it could not return.