Reverie Metherlence, called Ren, hails from the Metherlence bloodline and serves as her story's central figure. Her childhood unfolded in a secluded, snowy Edel Raid village, marked by severe bullying due to her status as one of the Shichiko-hoji (Seven Glittering Jewels), the most powerful Edel Raid lineage. This ostracism drove her to self-harm, attempting to remove her Elemental Gelade, the power-signifying stone above her forehead. Her only companions were her guardian, Griina, and an older Edel Raid named Sha, who provided support. Sha gave Ren a distinctive triangular-patterned ribbon to conceal her Gelade, replacing an oppressive hood that forced Ren to hang her head. This ribbon became a cherished symbol of their bond. After bandits attacked, a soldier named Keath intervened, leading to Sha's departure for Edel Garden with a reunion promise. This ignited Ren's lifelong obsession with reaching Edel Garden. She was subsequently captured and sealed in a coffin-like container for an extended period, later revealed as 500 years, leaving her unfamiliar with modern technology like airships.

Ren wields the elemental attribute of wind offensively and defensively, requiring frequent sleep to recharge her abilities. When reacting with a human partner, she transforms into a weapon—specifically, a large sword attached to her partner’s right arm. This weapon form differs between media: the anime depicts a smooth, pale cyan blade with peach-pink hues and a blue ribbon encircling the hilt, evoking a peacock feather; the manga shows a jagged, jade-green crystalline structure enveloped by swirling wind, blurring her physical form and elemental force. Her combat style emphasizes precision and speed, allowing her to cut through steel. She dislikes sweet foods and maintains a singular driving goal: to reach Edel Garden, which she describes as existing "because it doesn’t, and doesn’t exist because it does".

Initially cold and reserved, Ren exhibits blunt honesty and deep-seated mistrust of humans, viewing them as exploitative of Edel Raids—a worldview stemming from childhood trauma and isolation. Her demeanor shifts significantly after encountering Coud Van Giruet, a sky pirate who discovers her sealed coffin. Though she initially despises him for being human, his unwavering efforts to protect her during an attack lead her to "react" with him, forging a partnership. Traveling with Coud and their companions—Cisqua, Rowen, and Kuea from the Edel Raid protection group Arc Aile—exposes her to camaraderie and selflessness, challenging her prejudices and fostering empathy. Her development manifests in increased expressiveness: more frequent smiles, engagement in conversations, and displays of jealousy when others, like the artificial Edel Raid Viro, show interest in Coud. This jealousy inadvertently deepens her bond with him.

Ren’s relationship with Coud evolves from mutual reliance to profound romantic love. She chooses him as her permanent pledger because he treats her as a person, not a weapon—a stark contrast to prior experiences. His repeated declarations of protection and eventual confession solidify their bond. In the anime, their love breaks the Chaos Choir's control over her, highlighting their emotional connection. By the narrative’s conclusion across all media, Ren explicitly reciprocates Coud’s feelings. The anime shows her abandoning Edel Garden to join Coud aboard the Red Lynx airship, declaring they will "go beyond the stars together." The manga offers a more ambiguous ending: after Edel Garden’s collapse, Coud disappears, but footage later surfaces suggesting their continued partnership. Ren’s journey culminates in embracing her identity and future alongside Coud, symbolizing her transition from isolation to belonging.