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 for 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.
When Warsmith Honsou returned to the Iron Warriors' homeworld within the nightmarish realm of the Eye of Terror, he sent the newly obtained gene-seed to Warmaster Abaddon, but he secretly kept a small portion of the genetic material for himself. With his ill gotten gains, Honsou set about constructing an usual genetic system known as the Daemonculaba - which combined the application of technology and the arcane to create new Astartes to swell the ranks of the Iron Warriors Traitor Legion. This process required an adolescent human boy to be sealed within the womb of a genetically modified human female slave, known as a Daemonculaba, whom had been impregnated with the stolen Astartes gene-seed. The Daemonculabas either produced a horribly mutated freaks known as the Unfleshed (which were cast out) or a new Chaos-corrupted Astartes ripe for incorporation within the Iron Warriors ranks. The Daemonculaba hosts lay within Warsmith Honsou's fortress of Khalan-Ghol.
Refusing to uphold his predecessor's promise to share the stolen gene-seed amongst fellow Iron Warrior commanders, Honsou led his warriors in a brutal civil war with two rival Warsmiths -- Lord Berossus and the Chaos Dreadnought Toramino. Recently exiled from the Ultramarines Chapter, Captain Uriel Ventris and his best friend, Veteran Sergeant Pasanius Lysane were tasked to fulfill a Death Oath sworn by their Chapter Master Marneus Calgar. They accomplished this by traveling aboard the ancient daemon engine Omphalos Daemonium into the Eye of Terror and infiltrating the daemonic world of Medrengard. Once there, they were tasked with the impossible mission of seeking out and destroying the Daemonculaba.
Engulfed in civil war, Khalan-Ghol was under seige by Warsmiths Toramino and the Chaos Dreadnought Berossus. The Ultramarines enlisted the help of the former Raven Guard renegade Ardaric Vaanes and his group of Space Marine Renegades, infiltrating the fortress at the height of the siege. However, they were soon captured by Honsous's daemon-possesed Iron Warrior bodyguard, Onyx and taken to the halls of the Savage Morticians, Dark Mechanicus techpriests that had created and oversaw the Daemonculaba process. Once there, Uriel was entombed inside the womb of one of the Daemonculaba. Honsou showed great interest in Pasanius's bionic arm of living metal, for his arm was made from Necrodermis, the living metal that comprised the cybernetic bodies of the Necrons and their C'tan Star Gods. The Sergeant's bionic arm was removed and reattached for Honsou to wear. This enraged Pasanius against the Savage Morticians, as Uriel miraculously fought free of the Chaos-corrupted womb and made good his escape, along with a few survivors, down a sewage chute.
In the meantime, making one final push against Khalan Gol, the forces of Lord Berossus stormed Honsou's citadel. The two rival Warsmiths fought a titanic duel, but with the help of his daemon-possessed bodyguard, Honsou eventually emerged triumphant. With the death of their lord, Berossus's men defected to victorious Warsmith Honsou, and joined his forces against the rival Toramino. Leading a band of the Unfleshed, Uriel once again infiltrated Honsou's citadel and successfully destroyed the Daemonculaba. Captain Ventris also freed the Heart of Blood, one of the most favoured Daemonic avatars of the Blood God Khorne, which had been imprisoned by the Iron Warriors and forced to create and sustain an unbreakable psychic barrier around the fortress of Khalan-Ghol for over 10 thousand years. With the psychic barriers broken, Toramino was able to employ psychic attacks against his hated rival's citadel.
During the ensuing melee, Honsou and his retinue discovered and cornered both Uriel and Pasanius before they could flee the citadel. But before the Warsmith could have his retinue slay the upstart Ultramarines, the Unfleshed arrived on the scene and viciously attacked the Iron Warriors and slew them. Fleeing from the battle, Captain Ventris caught up to Honsou and shot him in the head with his Bolter. After having destroyed the fortress and the Daemonculabas, the pair of Ultramarines had fulfilled their Death Oath and returned to their Chapter. After the departure of the two Ultramarines, it is revealed that by some dark miracle, Honsou had managed to survive. The wounded Warsmith then later discovered the Heart of Blood, thoroughly exhausted from its battle with a daemonic rival and collapsed upon the floor of the ruined citadel. Employing the formidable powers of the Heart of Blood against Toramino's forces, Honsou eventually emerged triumphant, though his victory was a Pyrrhic one at best. Most of his forces has been smashed by the two rival Warsmiths and their armies during the internecine war. Despite his losses of both his men and the Daemonculaba, Honsou began the task of rebuilding his forces. He accomplished this by inviting those surviving Chaos renegades into his growing army. These renegades include the likes of the infamous Chaos Space Marines Ardaric Vaanes and Cadaras Grendal as well as a loathsome creature known as the Newborn - a clone of Uriel Ventris that had been created by Daemonculaba before its destruction.