TV-Series
Description
Doctor Heartless, former head of the Clock Tower's Modern Magecraft Theories department preceding Lord El-Melloi II, earned his moniker when a journey into fairy territory resulted in the theft of his heart, fundamentally altering him and contributing to his pre-narrative disappearance. He masterminded events across several major Mage's Association incidents.

During the Twin Towers of Iselma case, he sold Siegfried's catalyst to Touko Aozaki while informing Atrum Galliasta of its existence, deliberately concealing Touko's destruction of it to incite conflict between Atrum and Iselma. Seven years before the Rail Zeppelin incident, he coerced Holy Church agent Karabo Frampton into murdering mystic eyes user James Cavendish, suppressing Fourth Holy Grail War intelligence.

His primary scheme unfolded during the Rail Zeppelin arc. Using shapeshifting abilities, he infiltrated the mystic eyes auction train disguised as Caules Forvedge, Lord El-Melloi II's student. He murdered Trisha Fellows, Olga Marie Animusphere's governess with Mystic Eyes of Precognition, primarily to halt her investigations. His true objective manipulated the Rail Zeppelin onto a collision course with the vampiric Child of Einnashe, aligning them on a leyline convergence.

This convergence, combined with the presence of Waver Velvet (the sole surviving Fourth War Master not aligned with the Church), engineered the conditions to manifest a false Holy Grail. Though incapable of granting wishes, this Grail enabled him to summon an irregular "Faker"-class Servant: the unnamed twin sister of Hephaestion, who acted as a body double for both Hephaestion and Iskandar. Faker harbored resentment towards the crumbling of Alexander's empire and wielded abilities tied to her role. Heartless displayed a flamboyant, theatrically nonchalant demeanor even as his plans unraveled. While his precise motives for creating the false Grail and summoning Faker remained obscured beyond the scheme's execution, his actions targeted the Clock Tower's status quo and exploited Grail phenomena. After Lord El-Melloi II, Gray, and allies thwarted his Rail Zeppelin plot, he escaped custody.

His influence persisted. During the Grand Roll case, Atrum Galliasta, having deduced Heartless's role in the Iselma incident before his Fifth Holy Grail War death, left posthumously delivered data implicating Heartless. This information revealed his history, including hospitalization after returning from fairyland decades prior, and confirmed his ongoing manipulations targeting the Clock Tower's power structures, solidifying his role as a significant, lingering antagonist within the Mage's Association.