Honsou is a Chaos Space Marine of the Iron Warriors Traitor Legion. Honsou managed to claw his way to the esteemed position of Warsmith of his own Grand Company despite heavy prejudice from other Iron Warriors Astartes despite being a 'half-breed'. When Honsou was transformed into a Space Marine, his gene-seed was 'tainted' by captured genetic material from their hated rivals of the loyalist Imperial Fists Space Marine Chapter. Despite their prejudice, Honsou's abilities and tenaciousness help him succeed in achieving the nigh impossible.
Siege of Hydra Cordatus
During Abaddon the Despoiler's 13th Black Crusade in 999.M41, under the command of an unnamed Warsmith, attacked the Adeptus Mechanicus Forge World of Hydra Cordatus which supplied weapons and other war material to the Imperium at large, and was one of the few locations in the galaxy where the Mechanicus secretly stored its tithes of Space Marine gene-seed. Alongside his chief rivals Forrix and Kroeger, of the First and Second Grand Companies respectively, Honsou was one of three champions of the Warsmith that lay siege to the large citadel and manufactorum complex known as the Tor Christo. Deep within this formidable Imperial citadel lay the stasis vaults which contained the genetic material drawn from the Iron Warriors' most hated foes, the Imperial Fists Space Marine Chapter.
The Iron Warriors desperately needed the Astartes gene-seed to reconstitute their numbers as the corrupting power of Chaos tended to corrupt their own gene-seed to the point that it was unusable to replenish their ranks with new Chaos Space Marines. Honsou was often belittled be his fellow Iron Warriors for having mixed gene-seed which consisted of spliced Iron Warriors and Imperial Fists genetic material. He was referred by the derogative 'half breed', due to his gene-seed's dual heritage. Despite the Imperial forces arrayed against them, including a large garrison of Imperial Guard troops and even a small Titan Legion protecting its precious contents, in the end the Iron Warriors emerged triumphant. They defeated the Imperial forces defending Tor Christo as well as an entire company of Imperial Fists whom had arrived as reinforcements to try and prevent the theft of their genetic legacy.
Having greatly pleased the Chaos Gods through his monumental victory the commanding Warsmith was gifted with daemonhood. Before his final ascension as a Daemon Prince the Warsmith appointed Honsou as the new Warsmith, handing him the reigns of leadership of the Grand Company. He then commanded the newly appointed Warsmith to take the stolen Imperial Fists gene-seed back to the Iron Warriors' Daemon World of Medrengard within the Eye of Terror. After the forces of Chaos withdrew their forces they bombarded the remains of the citadel to dust, leaving behind a lone survivor to tell the tale of what had occurred.