A bright-eyed, quick-footed nine-year-old with an uncanny knack for noticing small details that everyone else walks right past. She moves through the neighborhood like she belongs to every corner of it, always on some errand or another for her guardian, a paper bag or bundle tucked under one arm and a cheerful word ready for every shopkeeper she passes. She has a gift for pattern recognition that she does not yet have a name for — she just knows when something looks the same as something else, the way she knew the diamond-in-circle stamp on the morning pastry matched the symbol on the note before she could explain why it mattered. She is generous almost to a fault, quick to share food, information, and her time, and she has a habit of arriving exactly when she is most needed. Though she can seem breezy and unhurried, there is a quiet attentiveness behind her easy smile — she listens carefully, remembers everything, and rarely forgets a face or a pattern.

Mei-Lin grew up learning to see the world in patterns, taught by a mother who was a ceramics artist and who treated every mosaic sidewalk like a story worth reading. After her mother's death when she was six, she moved to the riverfront neighborhood to live with her guardian and quietly rebuilt her sense of home one errand route at a time. The weekly Sweetline Bakefront delivery run became her anchor, and her habit of noticing small repeated details — a stamp, a symbol, a tile — became the gift that placed her at the center of the crew's investigation on the day she arrived with a paper bag and a pastry stamped with a diamond inside a circle.

A nine-year-old Chinese-American girl with a slight, wiry frame and the quick, sure-footed movement of someone who knows every crack in the sidewalk. Her black hair is worn in two low, slightly lopsided pigtails. Her round face is open and attentive, with deep brown eyes that move carefully over everything around her. She wears a soft quilted vest over a long-sleeve shirt, practical canvas trousers with deep pockets, and worn sneakers with bright laces. A paper bag from [[Sweetline Bakefront]] is almost always tucked under one arm, and there is a faint smudge of ceramic glaze on her left wrist that she considers a permanent accessory.