Beatrice Flowerchild serves the Ainsworth family as a resurrected doll, originally Julian Ainsworth's elementary school friend. She adopted her nickname, rejecting her unknown birth name. Bullied for her red hair, Julian's intervention sparked her confidence and deep affection. Her human life ended abruptly when Fourth Holy Grail War debris crushed her moments before confessing to Julian. Witnessing this devastated him, with Darius Ainsworth present.
The Ainsworths transferred her personality into a doll body, akin to other mages like Angelica. This resurrection erased most past memories and crucially, her capacity to love Julian. Despite this void, she wrestled internally with her situation and Julian's changed nature, often masking feelings with pragmatic duty-talk. Her doll form resembles a young girl with unkempt scarlet hair tied at the ends, yellow eyes, and a fang-like mouth. She favors goth lolita attire and carries an umbrella. As a human, she wore glasses and braided hair under a school uniform until Julian influenced her style.
Assigned the Berserker Class Card for the Fifth Holy Grail War, her objective was defeating Shirou Emiya. Her combat centered on wielding Mjölnir via the Card. "Including" manifested one enlarged, bandaged, gauntleted arm; "Installing" created a Norse-inspired outfit with fur cloak, buckled red skirt, and boots. Her fighting mirrored her volatility – she reveled in violent clashes but grew intensely irritated when opponents survived. This instability permeated her life: affection for Julian or stuffed toys could shift abruptly into depressive violence, like decapitating toys stolen from Erika Ainsworth.
Key conflicts saw her appear early with Angelica to recover Miyu, using Mjölnir's lightning to paralyze. Later, she ambushed Illyasviel von Einzbern and Tanaka at a playground and battled them in the Ainsworth castle's Mystic Code repository. During Illya's group's second assault, she aided Julian after Darius's conceptual replacement failed, destroying Shirou's projected weapon and repelling him from Pandora's Box. Her most significant battle involved guarding Pandora's Box's pathway alongside Sakura Matou in Fuyuki City. Overpowering Illya (using Berserker Install) and Bazett Fraga McRemitz initially, she dismissed Illya's plea ("What do you fight for?!"). Forced to adapt, Illya poisoned her via Rider Card (Medusa Gorgon) and manipulated her into reenacting Thor's fatal nine backward steps. This failed because her Card contained Thor's son Magni, whose divine core deemed retreat unforgivable.
Bazett's subsequent Fragarach pierced her heart but triggered Mjölnir's destruction via Magni's conceptual defense, unleashing Ragnarök and flooding Beatrice with fragmented Julian memories. As uncontrolled lightning threatened her existence, Illya rescued her by forcibly ejecting both Berserker Cards. Defeated, Beatrice despaired over reverting to emotionlessness or becoming a monster, questioning Illya's tears. Illya revealed knowledge of Beatrice's past: her crushed body's final moments and Julian's futile rescue attempt. Confronting her self-perception as a "disposable pawn" and "empty doll," Beatrice admitted losing her love for Julian upon dollification. Illya countered that Beatrice had unconsciously regained those feelings, prompting her emotional collapse and acceptance.
Post-revelation, Bazett returned Magni's Card, noting Beatrice retained her love despite Mjölnir's memory-sacrificing mechanics. Initially reluctant due to the cost, Beatrice accepted after Bazett emphasized how memory loss enabled forward movement. Later, during Darius's global mud crisis, her Class Card transformed from Berserker to Rider. Summoning Gullfaxi, she battled mud giants alongside Bazett, experiencing further memory erosion leaving only vague recognition of Illya and Chloe. After rescuing Julian and reuniting with Miyu, mention of "someone important" fully restored her memories of Illya and Chloe, leading her to encourage Miyu. In the "Licht Nameless Girl" timeline, her arc culminated in sacrificing herself alongside Julian against Pandora's manifestations, directly shielding him with her body – mirroring his childhood protection. This act demonstrated her complete reclamation of memories and devotion.