- "I... I see. Merciful God, you have sent me an apostle. Guard your life, son, you have a calling."
- ―Father Martin
A note found by the player describes a patient called "Father" Martin Archimbaud who has begun suffering from delusions of a "higher calling" after the asylum's art therapy program is done away with. The quotation marks around the word "father" in the note imply that his status as a priest is questionable. This origin is hinted at by the cross on his chest that appears to be fashioned from straps, and at times a buckle is visible. His religion worships the Walrider, as it's the only reasonable explanation he could suffice in his state of dementia. His past experiences with finger painting may have led him to mark the path for Miles in blood in the form of writing, arrows, smears, etc. Several notes in the game are written by him, such as this one.
He sees himself as a prophet of his god, the Walrider, and he believes that it is his duty to spread its gospel. He presents himself as a calm and good man only doing his duty, even apologizing to Miles for sedating him. His faith is so strong that he eventually burns himself on a cross, believing he will be resurrected and free. He was able to seize control of some of the inmates of Mount Massive Asylum such as The Twins, to the point that he was able to grant Miles free passage through certain sections of the building. However, characters such as Chris Walker and Eddie Gluskin are not under his leadership. Additionally, Trager seems to despise the priest entirely, which is evidenced by his rants before he mutilates Miles' fingers.
Miles first encounters Father Martin in the atrium after having been thrown through a window by Chris Walker. Seeing their meeting as divine intervention, he calls Miles his apostle and tells him that he has a greater purpose. After Miles wakes up from the blackout he is gone. Shortly after, he is seen on a monitor in the Security Control room, cutting off the power to the asylum. After Miles restarts the generator in the basement and returns to the Security Control room to open the main doors, Father Martin overwhelms him and injects him with a sedative. He says that he cannot allow Miles to leave, for there is so much yet for him to witness. He shows Miles security footage of soldiers being slaughtered by an entity called the The Walrider and that he has to accept the gospel so that all doors before him will open. Miles then blacks out and is transported by Father Martin to the holding cells in the Prison Block. Father Martin is then seen in certain areas throughout the game, sometimes instructing Miles to follow him through. He can be seen in the Sewer, walking past a blocked off passage while singing. The next encounter is near the end of the Male Ward after escaping from Trager, he exclaims that he is glad Miles survived, for he feared that Trager would carve him up like he did with numerous other patients, he says they're close now and that Miles should follow him outside to the Courtyard where he leaves a message in blood and a document near the flickering lantern post. Father Martin is seen next inside the Female Ward, waiting at the middle floor of a collapsed section, shouting if Miles saw The Walrider as well, he says Miles can cross from the upper floors to reach him. He is last seen in the Chapel, in the upper floors of the Administration Block, where he is crucified in a ceremony as a prayer to The Walrider and tells Miles to record his death. A document explaining the ritual can be found earlier in one of the rooms with a praying patient.
Martin makes a cameo appearance in the Prison. Waylon Park passes him as he is painting on the wall, "Down the Drain" for Miles Upshur, as he already was in asylum. He tells Waylon not to worry, for he is doing "his" work. Later in the DLC, Waylon can look out of a window in the Male Ward and see the exterior of the chapel, now ablaze in the aftermath of Father Martin's death.
Martin is completely delusional and blindly religious to The Walrider, acting as a calm priest who solely focuses on his religion. This warps him to see almost everything related to his religion, such as viewing Miles crashing next to him as The Walrider sending him an apostle. His devotion is both suicidal and murderous, willing to crucify and burn himself alive for the sake of The Walrider, and killed a man just to use his blood to fingerpaint "Down the drain" on the wall. This indicates he is more dangerous than he lets on (though one of his followers could have killed the man for Martin). Martin's document also says he likes fingerpainting.
Martin appears as a bald, chubby, and old man with a considerably creepy facial expression, in his 60's. He wears a garb of a black unbuttoned straitjacket with the back draping down to his ankles like robes. He also has black pants, matching slippers and beige straps around his torso and wrists that shape into a cross.
- Martin speaks Latin.
- In the game's configuration files, Martin is dubbed as "Priest".