Aquasteed Marineforest is the crown prince of the neighboring kingdom of Marineforest. He first appears in the story as a study abroad student in the kingdom of Lapis Lazuli, where he observes the protagonist, Tiararose, from a distance. While she is formally engaged to the crown prince of that kingdom, Aquasteed keeps his growing feelings for her a secret, respecting her existing relationship.

His defining moment occurs during Tiararose’s public condemnation, a scene from the otome game’s storyline where she is falsely accused, her engagement is annulled, and she faces exile. Aquasteed intervenes decisively, stepping forward without hesitation to propose marriage to her on the spot, thereby altering her fate entirely. This act demonstrates his most prominent personality traits: he is decisive, chivalrous, and acts on his convictions without internal conflict.

Aquasteed’s personality is characterized by a refined and wholesome kindness that is perceived as deeply sincere rather than performative or politically motivated. He is generally calm and composed, but possesses a quiet, observant nature, having noticed and admired Tiararose’s quiet strength long before their engagement. His love for her is described as bordering on obsessive adoration, yet it is portrayed as a healthy and mature form of devotion. He is protective and shows signs of jealousy when her safety is threatened or another man oversteps, but this is rooted in concern for her well-being rather than a desire for control. His focus is consistently on her happiness, and he respects her boundaries and supports her choices.

His primary motivation is to ensure Tiararose’s happiness and safety, having fallen in love with her naturally over time. As a crown prince, he is also trained to rule and takes his position seriously, though his personal feelings for Tiararose are the main driver of his actions throughout the story. In his role, he serves as the emotional backbone of the narrative, saving the heroine from her predetermined tragic end and standing beside her consistently afterward.

Key relationships define much of his role. His relationship with Tiararose is the central focus, characterized by his unwavering support, open affection, and a desire to make her feel valued and chosen. He also has a notable dynamic with a character named Keith, who serves as something of a trickster mentor or gadfly. Keith flirts with Tiararose and engineers situations that push Aquasteed to be more honest and demonstrative in his love, forcing him to confront areas where he may unknowingly cause Tiararose distress. For example, Keith points out that Aquasteed’s reluctance to upset a character named Icilla, due to her connection to potentially dangerous fairies, ends up hurting Tiararose’s feelings.

Throughout the story, Aquasteed experiences development, particularly in learning to communicate more openly. He initially makes the mistake of spending time with Icilla without fully explaining the political and magical necessity of keeping her happy, which leads to Tiararose’s insecurity and jealousy. Through external pressure and introspection, he learns to be more transparent with his motivations and more attentive to his fiancée’s emotional needs. He is also shown to struggle against external forces, such as fighting the effects of a love potion that threatens his agency and relationship.

In terms of notable abilities, Aquasteed is depicted as highly talented and intelligent. He is a skilled swordsman and is adept with magic, fitting for a crown prince in a fantasy setting. These skills, combined with his calm and strategic mind, make him a capable leader and protector, though he never displays arrogance about his talents.