Mordred Doussant, son of the merchant baron Baron Doussant, endured intentional exposure to a nemesis during childhood at his father's command. Though he survived, the infection left him psychologically altered, stripping him of typical human emotions while leaving his physical appearance intact. Baron Doussant subsequently dispatched Mordred to Cyfandir's capital, Caislean Merlin, as a sleeper agent. His mission: infiltrate the Order of Sorcerer Knights, join the extremist Faithful of the Hermit, and covertly monitor them. The ultimate goal was to spark a conspiracy forcing the Bôme and the Inquisition into military intervention, enabling his father to overthrow Cyfandir, enslave its infected populace, and seize the continent's resources.

Physically, Mordred is a young man with platinum blonde hair and a small goatee. He habitually maintains an innocent expression with his eyes closed. Opening them reveals clear eyes and a markedly less expressive face. On missions, he wears standard Sorcerer Knight armor and a green hooded cloak. In civilian life, he favors a white chainmail tunic with black trim over a billowy white shirt, white pants, brown leather gloves and boots, and a white medieval cloak with a black hood.

Outwardly, Mordred projects shyness and introversion. He displays apparent affection, particularly towards childhood friends Ocoho and Sagramor, adopting a close, familiar demeanor. This persona is entirely fabricated. The infection eradicated his capacity for genuine emotion or resentment. His behavior results from years of observing others, mimicking attitudes, and repeating learned phrases. Revealing his true nature exposes a cold, unscrupulous individual unconcerned with morality, operating solely on calculated objectives devoid of empathy or ethics.

Arriving in Caislean Merlin as a child for knight apprentice training, Mordred struggled socially. He meticulously observed Sagramor, whose rigid expressions amplified minor gestures, using this to refine his mimicry. He formed friendships with Ocoho and Lulu during this time. Ocoho confided the secret of her unique infection, information Mordred later exploited to ensure her knighthood for future usefulness. As children, Mordred, Sagramor, Ocoho, and Lulu explored the castle during the Investiture ceremony. Mordred, Sagramor, and Ocoho made a pact to attend the Investiture together, positioning Ocoho and Sagramor as key tools in Mordred's plans.

Years later, as a knight apprentice, Mordred established the covert "Faithful of the Hermit," recruiting Lords and apprentices like Sagramor and Lord de Gulis. The group preached that Cyfandir belonged solely to its people, denouncing foreign cooperation as treason against Merlin's legacy. Members swore loyalty to Queen Boadicée. In reality, Mordred orchestrated the group from the shadows. They operated in strict secrecy from a hidden castle basement concealed by illusion, keeping identities anonymous. Mordred and his father used the group's ideology to infiltrate Cyfandir with agents who made deals with peasants, deliberately marking them as Faithful targets.

A primary activity involved creating spectral nemeses using sorcerer Diabal's abilities. Employing a captured nemesis, a device, and a projection stone, they generated projections to attack fields of peasants dealing with foreigners. These attacks served as punishment, destroying fields while the specters' nature made them impervious to knights. Lord de Gulis would publicly "defeat" each specter to conceal the truth. Apprentices or knights demonstrating the ability to destroy specters were silenced by the Faithful, their deaths blamed on the specters. Only Mordred and Sagramor were allowed to succeed, embedding them as undercover agents. De Gulis took them on as pupils to maintain cover. Their standard strategy used a connection spell to instruct apprentices to "immobilize" then "weaken" the specter, before Mordred and Sagramor delivered the "final blow," facilitating years of punitive actions.

Mordred incorporated Ocoho into operations by exploiting her infection. Her curse compelled obedience to commands from anyone touching her infection mark, erasing her memory afterward. He used her to manifest as the legendary Dullahan, a headless fairy announcing spectral nemesis attacks, furthering the agenda and instilling fear.

During one spectral mission, Mordred observed a dejected Ocoho with a new squire. Feigning concern, he asked if she was alright and instructed her to await orders, noting the current specter's larger size. He and Sagramor followed protocol to immobilize and weaken it, knowing the attacks would pass through to destroy the fields below. When Ocoho unexpectedly disrupted the operation with a protective dome, severing Lord Brangoire's connection and fading the specter, Mordred urgently directed Sagramor to deliver the "killing blow" before exposure. Afterward, he witnessed Queen Boadicée unexpectedly appear to investigate the specters and Dullahan legend, subtly questioning the knights' actions and commending Ocoho's protective intent.