Timothy Laisenbach, a German boy aged six to nine, carries the Medusa virus—a deadly extraterrestrial organism inducing petrification. His parents’ bitter divorce and custody battle, dramatized in the film adaptation, fuel his emotional turmoil. Despite his youth, he displays unexpected resilience and maturity, covertly manipulated by Alice Roznovski to act as an unlikely guide through the facility.

After the survivors awaken, he bonds deeply with Katherine Turner, who channels her guilt over past maternal failures into fiercely protecting him. He affectionately calls her "Auntie," a bond solidified when Katherine sacrifices herself by transforming into a harpy-like creature to shield him from danger. Her metamorphosis embodies her idealized motherhood, and Timothy remains steadfastly loyal, refusing to abandon her even as she recuperates in isolation.

Captured later by Ron Portman, Timothy endures an incomplete forced metamorphosis into a beast soldier. The botched process leaves him with elongated fangs, a clawed fur-covered arm, and spiky hair mirroring Zeus’ beast army. These mutations grant him the ability to command a dragon-like mount, crucial for the group’s survival.

In the film, his childlike perspective contrasts starkly with the group’s grim reality: he views the monstrous threats through a lens of childlike excitement, likening them to a video game—a narrative device underscoring the psychological toll of their ordeal.

By the story’s end, he survives alongside Kasumi Ishiki, determined to reunite with his parents. The manga concludes with him reunited with Katherine’s harpy form, their unbroken connection symbolizing enduring loyalty and fractured hope.