"There is nothing in the arcane and blasphemous arsenal of the forces of Chaos that can compare to faith. With the power of faith, our weapons become shining instruments of deliverance that can cleave the mightiest daemon in twain. With the power of faith, our minds appear as slivers of pure agony to the daemon, driving into the wretched forms of those who would dare stand before us. With the power of faith, our words become commands that cause the daemon to cower and cringe in terror. I could meet my enemies unarmed without a shred of fear in my chest, for I know that the Emperor watches over me and guides my hand. So let them come. We shall show them what the power of faith can do."
- — Brother-Captain Arvann Stern
Grey Knights Brother-Captain Arvann Stern is an elite Daemonhunter and one of the longest-serving and most highly decorated Captains of the elite Grey Knights Space Marine Chapter. Even from his earliest years as a Grey Knight, Stern was believed to be well on his way to becoming one of the Chapter's Grand Masters, but instead his life took an altogether different course.
Throughout his nearly four Terran centuries of service to the Emperor he has been confronted by his mortal enemy, the Lord of Change known as M'Kachen. The Greater Daemon has continued to interfere with Stern's fate since their first meeting such that for every act of heroism or bravery performed in battle by the valiant Grey Knight, some inexplicable misfortune also befalls him.
Amongst the ranks of the elite Grey Knights, Arvann Stern is one of the longest-serving and most highly decorated Brother-Captains. In 855.M41, during one of his most famous exploits on the world of Antraxes, Stern confronted the Cult of the Red Talon and their daemonic master, the Lord of Change M'Kachen. Stern valiantly led the counter-attack against the vile Greater Daemon, striking at the heart of the Chaos Cult's temple. Despite being outnumbered, the Grey Knights slaughtered the damned souls of the foul cultists. Through the use of his powerful psychic abilities, Stern managed to perform the formidable feat of banishing the mighty M'Kachen back to the Warp. Normally such a feat was beyond the psychic abilities of a lone Grey Knight Astartes. From that moment on, Stern's fate was to become forever intertwined with that of the Lord of Change. M'Kachen vowed to devour the human's mortal soul, even if it took him an eternity to accomplish this task.
Thus began the long standing vendetta that has not yet found its end. One-hundred and one years since his initial banishment, in the year 956.M41, M'Kachen managed to enter the material universe once again. The loathsome creature possessed the body of an unwitting Chaos Cultist and laid a trap for Stern amongst the obsidian pyramids of the world of Sargotha. Of the squadron of 5 Grey Knights who set foot upon Sargotha, only Stern managed to survive the ambush. Stern still bears the scars of the vicious battle that occurred amidst the blinding sands between him and the daemon. However, M'Kachen managed to escaped unharmed. Since that day, Stern and M'Kachen have fought many times. Each time the Grey Knight ferrets out M'kachen and forces the Lord of Change into a direct confrontation, the Greater Daemon always flees the field, though not before slaughtering Stern's companions, leaving the Brother-Captain as the often unwounded, sole survivor of these encounters.
Despite the high cost to his Chapter, Stern's confrontations with the daemon is by no means a victory for M'Kachen, for the schemes being pursued by the daemon are always ended with his inevitable retreat, and the elimination of its mortal pawns. Each time Stern battles his arch-nemesis he garners fresh knowledge of the Greater Daemon's weaknesses, which fuels his hopes that one day M'Kachen will be defeated permanently -- either cast back into the Warp, or sealed within the technological prison of a Tesseract Labyrinth. What purpose the Lord of Change is hoping to accomplish by fueling this hope to his own ends is not known.
The Grey Knights' Iron Grimoire records that devious opponents like a Lord of Change are as apt to deceive and ensnare themselves as any foe. The possibility of finally vanquishing his foe feeds Stern's drive to constantly train and prepare, refusing promotion to the rank of Grand Master until he ends M'Kachen's threat to the Realm of Man permanently. Stern's Brotherhood supports their captain unflinchingly, their duty and honour extinguishing any mortal fear. The Grey Knights feel that M'Kachen will surely one day overreach himself, and on that day, Arvann Stern's sword will avenge all of the fallen Grey Knights the daemon has slain.
- Codex: Grey Knights (5th Edition), pg. 41
- Codex: Daemonhunters (3rd Edition), pg. 59