Fabian Oldenburg is a supporting character in the anime and light novel series Endo and Kobayashi Live! The Latest on Tsundere Villainess Lieselotte. He is a young boy who attends the Royal Academy of Magic as a special exception due to his prodigious talent in the arcane arts. His magical power is immense, but he struggles significantly with controlling it, a flaw that has led to notable incidents, including the accidental summoning of a dragon. Physically, Fabian is described as a child with blue eyes and short, black hair that reaches his ears.

Despite his genius-level magical ability, Fabian’s personality is heavily shaped by distrust and a deep-seated fear, particularly of tall adult men. This fear stems from a troubled history that is gradually revealed, and it causes him to be wary and withdrawn around many of the male characters in the story. His defensive and mistrustful nature is a core part of his initial characterization, but it is not an insurmountable barrier. Notably, he demonstrates a clear sense of safety and comfort when in the presence of Cecilie Riefenstahl and the other sisters of the Riefenstahl family. This sense of security is so pronounced that the sisters will physically intervene to block larger men, such as Baldur, from approaching him, showing a protective dynamic that allows Fabian to lower his guard. He also develops a strong attachment to Lieselotte Riefenstahl, a connection that becomes a source of both comfort for him and mild jealousy from Prince Siegwald, Lieselotte’s fiancé.

Fabian’s role in the story is primarily that of a supporting character whose cooperation becomes essential for the main cast. As the protagonists Endo and Kobayashi work to alter the game’s original storyline, they recognize that they will need help from the other capture targets, including Fabian, to face the looming threat of the ancient Witch of Yore. His immense, if uncontrolled, magical power makes him a potentially vital ally in the coming conflict. However, his deep-seated fear of tall men presents a challenge for the party, which includes several large male figures. Overcoming this fear and securing his aid becomes an objective, one that relies on the kindness and patience of characters like Lieselotte.

Throughout the narrative, Fabian undergoes subtle but significant development. He initially appears as a solitary and frightened child, but he begins to build trusting relationships. The story emphasizes that while his past has given him a tendency toward mistrust, he is capable of forming meaningful bonds, particularly with the Riefenstahls, who provide him with a rare sense of safety and familial warmth. His attachment to Lieselotte is a key part of this growth, as it shows him willingly reaching out to another person. The reactions of the other characters to this attachment, such as Siegwald’s jealousy, also help to integrate Fabian more deeply into the central social circle, pulling him out of his isolation.

In terms of abilities, Fabian’s defining trait is his status as a magical genius. He holds immense power that far exceeds what is normal for a child his age, but his lack of control is his primary weakness. This imbalance is the very reason he was sent to the academy: to learn how to manage and refine his overwhelming magical output. While his abilities are portrayed as potentially dangerous, like when he lost control and summoned a dragon, they are also presented as an incredible asset if properly harnessed. His development as a character is therefore tied to both his emotional growth and his technical growth as a mage, moving from a boy defined by his fear and lack of control to a potential hero capable of wielding his power for good.