Kan Lakan is a military strategist in the Li military and the head of the La clan. He is an eccentric man, good at playing go and shogi, and frequently visits the Verdigris House.
Unable to recognize faces due to his prosopagnosia, Luomen taught him to be able to see people's faces by identifying people as shogi pieces according to their roles and functions. Only a hand full of faces can be seen normally by him, one of which is Maomao's, who Lakan is strangely obsessed with.
He is Maomao's biological father and nephew to Luomen.
He slept with his lover, a high-ranking courtesan in order to lower her price. However, he left for a long military campaign before realizing that she became pregnant.
(Source: The Apothecary Diaries Wiki, The Apothecary Diaries LN, volume 2, edited)