Hohenheim serves as the Chief Researcher and head of the LCE (E.G.O. research) department, the team responsible for extracting and developing E.G.O. gear from Abnormalities. He debuted in Intervallo 5: LCB Regular Check-up, where his cold and dismissive manner initially made him seem like a minor antagonist-adjacent figure. His popularity surged after the LCE dungeon revealed his deeply buried guilt over surviving the fall of Lobotomy Corporation while his colleagues, including his right-hand man Johann, were lost. Fans responded powerfully to the contrast between his blunt exterior and his genuine emotional depth, making him one of the most discussed characters in the Project Moon fandom.

Hohenheim and Johann were colleagues at Lobotomy Corporation, where Hohenheim scouted Johann from the Backstreets and reluctantly accepted his offer to serve as a right-hand man. The pair proved highly effective together, with Johann's sociable nature compensating for Hohenheim's logical blind spots, helping their department win multiple Department of the Year awards. Their relationship took its most significant turn during Lobotomy Corporation's burial protocol, when escape pods ran out and Johann convinced Hohenheim to take the final seat, sacrificing his own chance to escape. This event left Hohenheim with deep, repressed guilt that formed the emotional core of his Fathoms arc. The JohaHohe ship remains one of the most active pairings in the Project Moon fan community on Archive of Our Own and Tumblr.

The LCE (E.G.O. research) department, headed by Hohenheim, is the research branch dedicated to extracting and developing E.G.O. gear from the Abnormalities that the organization acquires. In the Project Moon universe, E.G.O. refers to specialized equipment drawn from the essence of Abnormalities, granting the user powerful abilities tied to that Abnormality's nature. Hohenheim himself wears the AEDD E.G.O. suit, derived from the Shock Centipede Abnormality, recognizable by its distinctive blue long coat, large belts, and electrified nails on the shoulders. The LCE plush fan community frequently references the AEDD suit as one of the most visually iconic designs associated with his character.

Canto IX: The Unsevering significantly expanded Hohenheim's role within the story, moving him beyond his established position as Chief Researcher and into more direct narrative involvement. In this chapter, Hohenheim equips additional E.G.O. gear, including the Lamp suit from Big Bird and the Diffraction E.G.O. weapon from Dimensional Refraction Variant, both sourced from Lobotomy Corporation's former headquarters. His involvement in key confrontations during this arc, combined with the continued emotional threads from his Fathoms arc, has cemented his status as one of the most narratively developed supporting characters in the entire Project Moon continuity.

On the surface, Hohenheim presents as arrogant, blunt, and dismissive, frequently making haughty remarks and showing little patience for sentimentality. He prides himself on his intellect and openly competes with Faust for recognition within the organization. However, the layers beneath this exterior tell a different story: he is deeply loyal to those he considers his own, emotionally affected by loss even when he refuses to acknowledge it, and prone to repressing trauma by recasting painful decisions as purely rational ones. Fans describe him as a character who uses intellectual superiority as a shield, and his Fathoms arc, where the Sinners help him confront the guilt he has buried regarding Johann and his former colleagues, is frequently cited as one of the most emotionally resonant sequences in the game. His unique combination of abrasive charm and hidden warmth has made him a beloved figure among fans of the E.G.O. plush collecting community and the wider Project Moon fandom alike.