The strategist Rakan has literal face blindness. Everyone's faces are shogi pieces with their "rank" including his own family members. All except one courtesan Fenshen, Maomao's mother (and later Maomao. He can see her face.) He genuinely loved her and constantly visited the brothel for her. Then his elitist family gave him shitloads of work to keep him away from her for many years. His face blindness also gave this man severe communication problems (in other words, he is an asshole with no regards of other people's feelings).
Meanwhile, Fenshen got pregnant and is no longer "fit" for working at the brothel so her life became miserable. So she abused Maomao till some point in time. Then Rakan's uncle [the doctor] became Maomao's foster father.
Rakan then came by once he was free from his elitist family (He became the head of the house) and tried to gain custody of Maomao but he was an asshole. Maomao knows he is the 'real father' but doesn't care.
To Maomao, the doctor is her "genuine father". Rakan is just a creepy old asshole stalker