Kan Lahan is a character from Apothecary Diaries. He is a clever civil official, a numbers genius, and Maomao’s biological cousin who also acts as her adoptive brother. He is known for managing imperial finances, loving money, and viewing the world through calculations. He part of an eccentric family (The La Clan) known for extreme intellectual talents and unique personalities. He views the world through a numerical lens, analyzing situations, assets, and people based on data, calculations, and strategic value. He is exceptionally cheap, loves money, and constantly looks for financial leverage, sometimes trying to exploit others or situations for personal and clan profit. True to the eccentric bloodline and quirks of the La Clan, he behaves in odd, unsettling ways—such as proposing odd logical experiments or boundary-pushing ideas. Rather than doing the physical work or getting his hands dirty, he prefers to pull strings quietly from behind the scenes as a brilliant informant and political asset. Kan Lahan works as a civil official and accountant in the Outer Court of the Imperial Palace despite being only nineteen. Kan Lahan is a slender young man of average height with a highly intelligent, studious look. He is typically seen wearing the standard robes of a mid-ranking civil official, which reflect his formal role in the imperial court. He wears spectacles, which is a rare and distinct trait in his society. He has sharp, calm features with a generally polite but calculating expression. His dark hair is neatly tied up or styled under his official headwear. He wears a yuanlingshan (or yuanlingpao), a traditional round-collared robe commonly issued to civil officials. The fabric is a deep, dark blue. Underneath his primary official robe, a clean white inner collar (zhongyi) peeks through at the neck. He sports a traditional official's hat known as a futou, which features stiffened wing-like extensions sticking out from the back. He wears dark, high-top court official boots, historically referred to as zao. He is rarely seen without his abacus, which he carries with him everywhere to tally up numbers, finances, and calculations.

Maomao is the sharp-witted, poison-obsessed protagonist of The Apothecary Diaries. She is characterized by her pragmatic and aloof demeanor, an intense fascination with medicine and toxins, and a fierce sense of personal autonomy. She mostly prefers to keep a low profile and avoid court politics, viewing medical mysteries and poisons as a fascinating hobby. She's highly protective of her own boundaries and values self-reliance over status or wealth. She is entirely uninterested in traditional court ambitions, power plays, or romantic seduction. Maomao's physical appearance and clothing are designed to reflect her practical nature and her life as a servant, masking a remarkably attractive appearance that surfaces only when she is dressed up. She petite, scrawny, and short (canonically standing at 153 cm or 5 feet tall) with a flat-chested build. She has dark forest-green hair and deep blue eyes. Her hair is worn in a half-up messy bun secured with a blue bow, while the rest is split into two low ponytails framing her face. These are tied with small red/pink and sky-blue beads. She covers her nose and cheeks with fake freckles made of clay and oil. She applies these to look plain and avoid unwanted attention or sexual harassment. She keeps her left forearm heavily wrapped in white bandages. This conceals numerous self-inflicted scars from testing poisons and remedies directly on her own body. She wears a light green robe layered over a white inner shirt, featuring a distinct dark green and pale collar. A long, flowing burgundy/deep pink maxi skirt. And simple, unadorned dark green flats built for walking and working around the palace.