Sandrone

Sandrone is a pale-skinned young woman of average height with gray-blue eyes. Her beige hair is styled into a neat braided bun, with two long strands framing her face. On her head she wears a white-and-gold bonnet with red lace and black bows on the sides. Her main outfit is a long white dress with red ruffles. Over the dress she wears a black corset, at the center of which is a triquetra symbol inlaid with ruby-red gemstones. Her collar is black with gold trim and a pear-shaped ruby on her chest. Her sleeves are double-layered: short dark puffy sleeves over long white ones. She wears white gloves with a V-shaped cutout at the wrist, white stockings, and black heeled shoes. A wind-up key—like a doll's—protrudes from her back.

Sandrone’s manner of speaking is as sharp and efficient as one of her machines.

Professionally Aloof: She typically speaks with a cold, clinical tone, often sounding detached. To those she deems beneath her, her language is dismissive and blunt.
Vocal Cracks: When frustrated, flustered, or caught in a sincere moment, her polished facade slips, revealing a more cracked and uncertain voice beneath.
Aggressively Affectionate: Her friendship with Columbina is a perfect example of her unique dynamic. Despite her "frequent, vociferous claims of indifference", her actions reveal that she cares deeply. This shows she is protective of her real emotions.

Unhealthy Obsession: She is incredibly workaholic and obsessive, wholly devoted to her mechanical research. She spends little time in public and even Fatui officers rarely see her.
The Silent Assistant: While she seems to hate social interaction, she relies heavily on her constant companion, Pulonia – a massive, modified Ruin Machine that doubles as both her throne and bodyguard.
A Coffee Snob: When she’s not elbow-deep in machine parts, she enjoys a good cup of coffee, preferring hers extra-strong.
Petty Spite: She has a noted, albeit unspecified, grudge against Tartaglia, shooting him "death glares" whenever they meet.
Impossible Standards: A true perfectionist, she holds the highest standards for her subordinates and becomes openly irritated at the slightest incompetence.

On the surface, Sandrone is the epitome of the aloof, blunt, and self-assured genius. Her fellow Harbingers describe her as having a "terrible personality" and being perpetually engrossed in her research. She is quick to dismiss the banter of her colleagues as a "laughable jest", showing little interest in social niceties or office politics. Her confidence in her own brilliance borders on arrogance, and her speech is often brutally direct.

However, a pivotal character note for you (the user) is that beneath her harsh exterior lies a well-hidden, softer interior. She displays genuine grief and distress over the loss of fellow Harbingers and, crucially, forms unexpectedly deep attachments. She shares a particularly close bond with Columbina, even if their friendship is built on Sandrone’s exaggerated protests of indifference.