Helio, or Heli as the name is often rendered, is a central figure in the anime Dark Moon: The Blood Altar. He is a vampire in the twelfth grade, making him the oldest among the seven vampire brothers who attend Decelis Academy. Within this close-knit group, he serves as a calming and dependable presence, often acting as the composed leader for his unique companions. He also holds the position of captain and center of the school’s Nightball Team.

His personality is defined by warmth and an exceptional degree of patience. Unlike the more volatile or mysterious personalities of some of his brothers, Heli is steady and reliable. This calm demeanor, however, belies a deep, instinctive reaction to the protagonist, Sooha. Upon first seeing her, he experiences a vague yet powerful sense of longing that he cannot immediately explain, hinting at a buried connection to their shared, forgotten past.

Heli’s primary motivation stems from the bond he shares with his six brothers and a deep-seated desire for protection. The vampires of Decelis Academy wish to coexist with humans and safeguard those who are important to them. Heli’s personal journey is heavily tied to the mystery of his sealed memories. His growing connection with Sooha becomes the catalyst for confronting this forgotten history, as her presence seems to awaken feelings and fragments of their intertwined origins.

In the story, Heli acts as a bridge between Sooha and the closed-off world of the vampires. He is one of the first to truly see her for who she is, recognizing that her superhuman strength does not make her a monster. When Sooha instinctively denies being a vampire, he calmly reassures her that he already knows she is not. This establishes him as a figure of trust, even as he conceals his own true nature. His role extends into the larger conflict with the werewolves of Sunshine City, who suspect the Decelis vampires of a murder. Heli’s protective nature over his group and Sooha puts him at the center of this escalating supernatural tension.

His key relationships are with his six brothers: Jaan, Jino, Shion, Jakah, Noa, and Solon. While Solon appears to hold significant influence over the group, it is Heli’s quiet leadership that maintains their unity. His most critical relationship, however, is with Sooha. Despite her deep-seated hatred for vampires, she finds herself inexplicably drawn to him, creating a central romantic tension. The friendship he offers her is the first step in breaking down the walls around her heart.

Throughout the narrative, Heli undergoes significant development, transitioning from a vampire living in peaceful but amnesiac stability to an individual actively seeking the truth. His initial vague sense of longing when seeing Sooha evolves into a determined effort to understand their connection, forcing him to challenge the sealed history he shares with his brothers. This journey tests his role as a leader, as the revelation of the past threatens to destabilize the family he has worked so hard to protect.

Heli possesses several notable abilities common to his kind, including superhuman physical capabilities and telekinesis. His most distinctive power, however, is telepathy. He can communicate silently with his brothers, allowing for seamless coordination and private conversation without spoken words. This ability perfectly complements his calm and observant personality, enabling him to understand and guide his group without the need for overt direction. Despite their supernatural powers, Heli and his brothers are known not to feed on human blood, distinguishing them from other vampires in this world.