Damian Desmond is the second son of Donovan Desmond, the leader of the National Unity Party of Ostania, and his wife, Melinda Desmond. He is a first-year student at the prestigious Eden Academy, where he has been placed in the same homeroom and dormitory, Cecil Hall, as his classmate Anya Forger. Physically, Damian is a young boy with neatly trimmed short dark brown hair that can have a slight greenish-olive tinge, and amber or hazel-colored eyes. He typically wears the standard black uniform of Eden Academy, and his expression often carries an air of condescension.

On the surface, Damian presents as an arrogant and prideful individual, a trait stemming from his upbringing as the child of a powerful and influential family. He initially looks down on others, including Anya, whom he perceives as being of a lower social class. On his first day of school, he mistook Anya's staring for romantic interest and boasted about his family, an encounter that ended with Anya punching him in the face. However, this initial conflict laid the foundation for a complex shift in his personality. After Anya delivered a tearful apology, Damian developed a crush on her, a fact he is deeply embarrassed by and refuses to acknowledge. This behavior is classic tsundere: he is often rude or dismissive toward Anya, making excuses to avoid her, while simultaneously becoming flustered and jealous when she interacts with others or sees through his true feelings. Despite his haughty exterior, he has shown an innate sense of integrity, such as when he dislikes people who approach him solely for his family name, and he instinctively steps in to protect Anya when she is in danger.

At his core, Damian is motivated by a deep, unfulfilled yearning for his father's attention and approval. The relationship with Donovan Desmond is distant and cold, leading Damian to believe that affection must be earned through exceptional achievement. His primary goal is to become an Imperial Scholar, just like his elder brother, Demetrius. This drive compels him to study diligently, a pursuit for which he has been rewarded. He earned his first Stella Star for scoring in the top two of his class on a history midterm exam. His second Stella Star was awarded for his brave actions during a school bus hijacking, where he volunteered to take a bomb collar from Anya. While he is a strong student, particularly in history, his academic weak point is his native language studies. Outside of academics, his hobbies include playing football/soccer, and he owns a pet dog named Max.

Within the story, Damian serves as a key figure in Operation Strix, a spy mission where his classmate Anya is tasked with befriending him to get close to his father. His most significant relationship is the complicated and evolving one with Anya Forger. What begins as a feud slowly transforms into a genuine friendship, with Damian often silently supporting her or being the recipient of her unfiltered honesty. He is also almost always seen with his two loyal best friends and followers, Emile Elman and Ewen Egeburg, who share in his punishments and support him. His relationship with his mother, Melinda, is more complex; while she came to pick him up in tears after the hijacking, she often refrains from showing active concern, and Damian is aware of a certain ambivalence in her feelings. He has a more distant and strained rapport with his older brother, Demetrius, who refuses his requests for academic help and does not understand Damian's admiration for their father. In terms of abilities, aside from his academic intelligence and a notable level of physical endurance and toughness, as demonstrated during a dodgeball match against a much larger opponent, Damian possesses no special powers or supernatural abilities.