Solitär

Small and slight, Solitar has green eyes and long, raggedly cut turquoise hair falling past her torso. A pair of tiny horns barely clears her forehead, parting her front bangs, and a tube-shaped pendant hangs from her necklace at the chest. When she first met Macht she wore a sleeveless yellow dress with twin lapels over a white underlayer, bracelets on both wrists, and ribboned sandals. In the present she keeps the same look but adds an orange cardigan.

Solitar is an oddity among demons, devoting herself to studying living things rather than to combat and magic. She knows biology intimately, grasps ideas as advanced as evolution, and can distinguish creatures like sharks from orcas, even keeping a converted human dwelling stocked with specimens and grimoires. Outwardly she is gracious, hosting Macht with tea and sweets though the courtesy goes unreturned, and she mimics human habits even with no one to see them. She can name a feeling like grief while insisting demons can never truly share it, and, unusually for her kind, she shows warmth toward other demons, calling those lost in the Demon King's war her friends and fretting over her race's survival.

What sets her apart most is her wariness of humanity. By her own admission she is too cowardly, fearful, or simply too wise to ever underestimate people, and she holds their potential and their magic in high regard, regretting that she must destroy the Great Barrier she so admired. For this reason she hides her identity and keeps her distance, refusing to let the arrogance typical of her kind cloud her judgment. Though fascinated by Macht's and the Demon King's dream of coexisting with humans, she believes it impossible and dangerous, convinced that the demons' very lack of empathy is what has spared the race from extinction. She studies human emotion rather than seeking to feel it, and Frieren regards her as the demon who understands the human mind best, a gifted manipulator whose interest resembles that of someone prodding a caged animal.

Long ago, the Demon King himself taught Solitar the concept of convergent evolution, and her brushes with humankind bred the wary respect that defines her. Roughly a century before the present, Macht of the Golden Land sought her out with questions about feelings unique to humans; she told him demons could never know such things, but his refusal to give up intrigued her, and she went on to introduce him to human magic. Later, when a future Frieren was cast into the past, Solitar gathered the Greater Demons Rivale, Tot, and Grausam in a bid to have Grausam steal Frieren's memories and kill her. She is also implied to have leveled an entire fortress city in the far north on her own.

In the present, Solitar arrives at the Great Barrier sealing the cursed city of Weise, drawn by the prospect of watching Frieren and Macht collide. She admires the barrier's intricate human magic and spends two months unpicking it before her own mana shatters it, finally alerting Fern and Denken to a demon whose power rivals Macht's. After offering the indifferent Macht her help, she runs into Fern and Stark, who have stayed to delay her. Feigning harmlessness, she claims never to have killed a soul, but Fern attacks, and Solitar answers by conjuring an army of mana blades, impaling both her opponents while peppering them with questions about their lives, since concepts like family fascinate her. Fern's densely packed Zoltraak eventually pierces Solitar's pure-mana defense and wounds her shoulder, a strike that could have been fatal aimed at the heart, only for Macht's spreading Diagoldze curse to freeze Fern and Stark into gold and end the exchange.

Solitar next cuts off the fleeing Denken, who escapes death only by surrendering to the gold curse, then reports to Macht that Frieren, having once undone Aura's Auserlese, can likely break Diagoldze too. When Frieren frees herself and reverses Denken's curse, both demons close in. Denken takes on Solitar while Frieren duels Macht, and Solitar wears Frieren down with her signature mana strike, a raw blast of mana dense enough to punch through Frieren's defenses. She lies that she has killed Frieren's companions, but Fern, very much alive, strikes her from beyond her mana detection with a long-range Zoltraak; Solitar murmurs her admiration just before Frieren delivers the killing blow. Earlier, in the failed ambush at the Goddess's Monument, she had backed Grausam's sleep spell with her blades until Himmel severed Grausam's arm, after which she called off the attack and withdrew.