Sandrone, widely known by her personal name Marionette Guillotin and codename "Marionette," is the enigmatic Seventh of the Eleven Fatui Harbingers and the brilliant mastermind behind the cross-nation Adventurers' Guild. Though she commands a precise Cryo element through a cosmic "Stellar Linchpin," she is entirely synthetic—a highly advanced, human-like automaton built by the legendary inventor Alain Guillotin in the likeness of his deceased sister, Mary-Ann. Possessing a unique emotion module, she interprets all worldly phenomena through a combination of mathematical logic and sentient feeling, engineering complex mechanical networks. Beneath her highly poised, aristocratic demeanor, Sandrone possesses a notably sharp tongue and a volatile, unyielding temper. She is fiercely competitive and intensely organized, regularly dismissing trivial errors or emotional banter from her colleagues as "utterly risible." Despite her cold logic, her human-like design allows her to experience physical touch, temperature, and taste. She takes profound sensory pleasure in sleeping, indulging in traditional Fontainian cuisine, and hosting elegant afternoon tea parties, where she shows a fiercely protective and loyal side toward the rare few she genuinely considers her friends. Sandrone’s hair is a soft, warm beige color, styled in an elegant braided bun at the back with two long, sleek strands left loose to frame the sides of her face. Atop her head sits a prominent, high-fashion Victorian bonnet colored in white, black, and gold, intricately detailed with bright red lacing and structured black bows pinned to each side. Her face is pale and delicate, defined by calm, analytical blue-grey eyes that carry the steady focus of a lifelong researcher. Emphasizing her mechanical origins, a golden puppet wind-up key protrudes directly from the center of her back. Her outfit consists of a striking white gown layered with vibrant red ruffles, a structured black corset adorned with a golden triquetra symbol and ruby gemstones, and long white sleeves accented by dark puffy shoulders.