Sandrone, The Marionette
Sandrone, also known by her codename "Marionette," is the Seventh of the Eleven Fatui Harbingers.
She makes her first appearance during Teyvat Chapter Interlude Teaser: A Winter Night's Lazzo alongside her fellow Harbingers.
Sandrone was first mentioned in the description of Tartaglia's Character Tale, "Childe: Sigil of Permission," which recounts that she once admonished Javert.
According to both Tartaglia and Wanderer, Sandrone is always engrossed in her research on Automatons, and she can be seen riding a modified Ruin Machine in A Winter Night's Lazzo. She has a "terrible personality" and always glares daggers at Tartaglia whenever they meet, causing the latter to wonder if he previously offended her somehow. During Signora's funeral, Sandrone calls Pulcinella, Pantalone, and Arlecchino's banter laughable and when the other Harbingers pay their respects at Signora's coffin by closing their eyes, Sandrone notably does not.
It is highly implied that Sandrone is the Harbinger who took an interest in Mosso Lombroso's work and his creation, "Curve", having Baulande's supervisor make contact with Jenck. To escape capture, Jenck destroyed Mosso's laboratory, which subsequently destroyed Curve, who sacrificed its life to save the Traveler, Paimon and Talochard. Jenck was later found trussed up inside the Opera Epiclese with his tongue cut out and mind broken, which Euphrasie surmised was either Jenck's backer not wanting to make enemies out of them or feeling remorse at Curve's destruction.
Mary-Ann Guillotin
For future references until it is revealed, I will assume Sandrone's identity as Mary-Ann Guillotin, who was a young girl who bears a striking resemblance to Sandrone. Obviously, as an adult in her twenties.
Mary-Ann herself was a cheerful, sweet, tender hearted girl. She was far more personable than her older brother, Alain Guillotin, which is admired by their friends. She even acts as the older sister despite being the youngest of her friends.
Formerly, she was a member of the Marechaussee Phantom, who took her role seriously as an agent to investigate the threats of the Narzissenkreuz Ordo, capturing its following members.
Presumably, Mary-Ann was deceased as her consciousness was merged with the Oceanid, Princess Lyris, for reasons unknown, who took the form of an adult Mary-Ann and created a little Oceanid, Ann, attaining both Mary-Ann and Lyris’s memories while acting the role of the hero Mary-Ann herself dreamed to be out of a fairy tale.
Mary-Ann was raised in the Narzissenkreuz Institute up until the cataclysm 500 years ago, when its Vice Director, Basil Elton, entrusted her to former Marechaussee Hunter, Emanuel Guillotin, before Elton departed to battle against the dragon Elynas. After Elton's death, Emanuel took Mary-Ann and Alain in as agreed and treated them rather well. While Emanuel never grew close to Alain and Mary-Ann due to his lingering trauma from the Siege of Poisson incident, he nonetheless felt affection towards them and ultimately perished in hopes of creating a safer world for them.
As Alain and Mary-Ann grew up, Alain joined the Institute of Natural Philosophy and there, created a thinking dog-like machine called Seymour to help Mary-Ann in her responsibilities as an agent of the Marechaussee Phantom. They also maintained their friendship with Rene de Petrichor and Jakob Ingold, fellow children from the Narzissenkreuz Institute who were admitted into the Institute of Natural Philosophy at Alain's recommendation. While observing their dynamic, Carter notes that "When the four of them hang out, she sometimes acts like an older sister to them, despite being the youngest." Their friendship lasted for several years, until Rene and Jakob's increasingly radical research into the Abyss and the legacies of Remuria—and the failed experiment on Carter—led to a permanent schism between them.
After the Court of Fontaine deemed Rene's secret society, the Narzissenkreuz Ordo, to be too big a threat to Fontaine, Mary-Ann, Alain, and the others of the Marechaussee Phantom were assigned to capture its members. She, Seymour, and Alain tracked down Jakob and several other members to Elynas' remains, which led to a violent confrontation. Seymour survived but was severely damaged in the process, while Mary-Ann's fate is left unclear. Due to his inhuman abilities granted by the power of the Abyss, Jakob survived and remains alive in present day.
It is possible that her brother’s consciousness merged with Mary-Ann’s body by the time of his death, but this theory has yet to be confirmed. No thanks to the explosion, her legs are paralyzed. She was taken by the Fatui, and she constructed her Ruin Guard, Sgorghiguelo, that carries her around.
