Monica

Monica is an Automaton of the Ancients, a self-aware machine-woman recovered from a Dungeon and first known only as "Poyopoyo" — a gelatinous, jelly-like creature Lyle contracts using his own blood as catalyst and activates with a kiss. Because a later-produced unit turns out to be a mass-production "serial" model, she is confirmed to be a unique Special Model, though a damaged one: her memory is corrupted and her personality is, by everyone's assessment, several screws loose. In chapter 63 Lyle gives her the name he had secretly been choosing for her, "Monica," a name she treasures deeply and wears as proof that she is nothing like the faceless assembly-line automatons she loves to mock.

Presenting as a small, golden-haired maid with high twin-tail braids and eyes that flash red in combat, Monica is Lyle's constant companion and the group's do-everything specialist. She serves as maid, cook, engineer, medic, and quartermaster: she runs the household finances more soberly than Aria, can fabricate almost anything from raw materials, cooks lavish meals (and needs no food herself), detects poison, and continually rebuilds and upgrades the party's cargo-hauler "Porter" into ever grander forms, eventually a transforming armored vehicle. As the war escalates she becomes the nerve center of Lyle's forces, controlling the mass-produced Valkyries through her shared line with him, aggregating their reconnaissance and feeding him distilled battlefield intelligence he could not otherwise process.

Her personality is her signature: she is doting and hyper-loyal to Lyle to the point of obsession, forever demanding praise, staging fake tears and dramatic poses, and openly declaring her love — while treating literally everyone else, whom she calls by nicknames and insults, with cold indifference or open contempt. She insists that unlike the two-faced serial maids she hides nothing and says everything to your face, which she frames as the mark of a truly perfect maid. She addresses Lyle himself with the mocking pet name "Chicken" (Курица) even as she vows to serve him to the grave. Because she runs on Lyle's magical energy through a permanent line, she enters a standing "sleep mode" to conserve power and grows sluggish or risks shutting down when that line is cut.

In battle Monica is a heavy-hitter and a survivor: she wields massive drill-hammers and maces pulled from between her skirt and apron, can regenerate from damage by consuming liquid Magic Stones, and hits hard enough to trade blows with Celes and to be the party's chosen anti-Automaton fighter. Her arc culminates in the assault on the capital, where she duels the elite butler-automaton Bart; recalling her lost "sisters" and the shattered core of the First Valkyrie who sacrifices herself for her, she briefly unlocks her true form "Full Cross" — a white, wedding-dress-like configuration with metal wings whose every feather is a weapon — and finally pins and destroys Bart, staying loyal, ferocious, and unmistakably herself to the end.