Meric Voyen was the company Apothecary of the Death Guard Legion's 7th Great Company that was commanded by Battle-Captain Nathaniel Garro during the Great Crusade and the opening days of the Horus Heresy.
Meric Voyen was the Apothecary of the 7th Great Company and the long-time friend and confidante of its commanding officer, Battle-Captain Nathaniel Garro. When Horus became corrupted by the powers of Chaos he instituted the mysterious warrior lodges within the various Space Marine Legions under his command. This practise was picked up after the Luna Wolves had made contact with the Feral World of Davin and their introduction to the warrior lodges of the Davinite tribes. It may be that this benighted and thrice-cursed world was the source of the cancer that would later grow at the heart of the Legiones Astartes, as the existence of these warrior lodges spread from Legion to Legion like a slow contagion. The warrior lodges were closed brotherhoods of Astartes within each Legion that existed outside of all other formal Legion structures. From what little is known of the practice in the present day, behind closed doors the members of a warrior lodge put aside the divisions of rank and honour. No ranks existed between members aside from the ranks and divisions of the lodge itself. Such subversion of the order of Astartes rank and military discipline was possible because the lodges bound themselves with ritual and secrecy.
Garro was furious with Voyen when the Apothecary confessed that he was a member of the secret warrior lodges that had begun to spring up in the XIV Legion. Garro let it be known to his men that he did not approve, for he felt that these lodges, though they had their worth, were ultimately predicated upon secrecy and the act of concealment which was anathema to the Astartes, and he would take no part in it. He later pulled Voyen aside and confronted him in private. Though he formally censored the Apothecary for being a member of the Death Guard's warrior lodge, he made the Apothecary swear to him that he would never keep any secrets from him. Voyen readily agreed, but knew in his heart that it would take much to regain his commander's trust.
During the Istvaan Campaign, Garro’s 7th Great Company fought in concert with the Emperor's Children’s elite 1st Company against traitorous forces on Istvaan Extremis, the outermost planet within the Istvaan System. Whilst fighting against a powerful Slaaneshi psyker known as a Warsinger, Garro sustained serious injuries that included crushing damage to his torso, arm and the loss of his right leg from the mid-thigh down. He was only saved from certain death by the timely ministrations of an Apothecary from the Emperor's Children Legion -- their Chief Apothecary Fabius -- much to Voyen's displeasure. The Legion’s Apothecaries had not declared him fully healed and therefore Garro was deemed unfit for battlefield operations. His command also remained on limited duty until Garro was fit to reenter combat. As a result, Garro and his company were not among the Death Guard Loyalists assigned to unleash the speartip assault upon Istvaan III, so they remained aboard the Frigate Eisenstein providing standby tactical support for the Drop Pod deployment operation, and remained on alert to perform rapid-reaction interdict duties.
Before the mission began, First-Captain Calas Typhon pulled aside Commander Ignatius Grulgor, the Captain of the Death Guard's 2nd Great Company, and spoke to him of their Primarch’s desire to bring Garro to Horus' banner over the Emperor's, but they both knew that Garro would never betray the Master of Mankind. When the turning point arrived, Typhon informed Grulgor that there were certain duties that Horus wanted him to perform. The Commander relished his part in this conspiracy against Garro, whom he had long found insufferable.
Aboard the Eisenstein, suspicious of Commander Grulgor's actioins, Apothecary Voyen stealthily made his way to the launch bay to investigate. Voyen saved Garro's Housecarl Kalab from narrowly being captured by Grulgor’s men. Kalab shared with Voyen that he had seen Grulgor and his men loading an unusual cargo aboard the frigate. Digesting what the housecarl told him, Voyen realised with growing horror that the deadly cargo were Life-Eater virus bombs – biological weapons of mass destruction that contained an engineered viral strain of such complete lethality that it could only be deployed in the most extreme circumstances, usually against the most foul xenos. Informing his commander of Grulgor's actions, Garro decided to confront the treacherous commander. With only Apothecary Voyen, Battle-Brother Sendek and his housecarl, Garro confronted Commander Grulgor and his entire Command Squad and a handful of the frigate's crew. A vicious fight ensued and Garro and Voyen narrowly avoided death. Grulgor and his men suffered the lethal effects of the Life-Eater pathogen when it was accidentally released by a stray Bolter round that punctured one of the warheads, and Grulgor and his men died screaming in agony.
During their flight to Terra to bring warning to the Imperium of the treachery of Horus, Voyen second-guessed his commander's actions multiple times, but ultimately, Garro's desperate gamble of detonating the Frigate's Warp-Drive when they became trapped in the Warp and were under assault by the undead Plague Marines of Nurgle, proved successful in bringing Loyalist aid. The crew of the Eisenstein were rescued by the Primarch Rogal Dorn and his Imperial Fists Legion. Aboard the Phalanx, they brought word of Horus' treachery to his stern brother. The Imperial Fists then brought Garro and his men to Luna, where they were imprisoned within the Somnus Citadel of the Silent Sisterhood. One of Garro's men, Solun Decius, finally succumbed to the mysterious contagion he had contracted when the Loyalist Death Guard were confronted aboard the Eisenstein by the reanimated corpses of Grulgor and his men -- the first true Plague Marines. A vicious battle ensued within the Citadel and out on the airless plains of Luna, and Garro was able to destroy the Chaos-tainted daemon that had possessed Decius' tortured body. Following this final battle, Voyen informed Garro of his intentions to renounce his oaths as a warrior in order to dedicate his life to healing and the discovery of a cure for the mysterious contagion contracted by Decius, which was later identified as the first known case of Nurgle's Rot.
- Flight of the Eisenstein (Novel) by James Swallow