Brother Martin, also known as Marty, was a member of the Kindred, a secluded, abstinent community in rural Massachusetts. He had left the commune to live amongst the outsiders after developing hypersexual interests in both sexes, which first started when he and his friend Brother Andrew found adult magazines on the outskirts of the forest. He would seduce both men and women into having intercourse with him using human pheromones. They would subsequently die of shock induced by the chemical reaction. He killed 6 people and nearly a seventh, before Mulder and Scully tracked him down to a shabby hotel, where he was abducted by his fellow Kindred, disappearing off the face of the earth alongside them.
Marty was portrayed by Peter Stebbings in his male form and Kate Twa in his female form