Mother Choi was the abusive, alcoholic mother of 707 and Unknown as well as the ex-lover/former mistress of the current Prime Minister of South Korea and a presidential candidate of the current election.
While she was alive, she an abusive and manipulative woman. Because the twin's father was a high-profile and married politician, she used the fact that she was his mistress and that she had children by him to her advantage to blackmail and to extort money from him, which she would mainly use for alcohol.
The twin's mother often used their father's position to strike fear in them and to keep the boys in line. She constantly told the boys that their father would send people to kidnap them and kill them, and if it wasn't for her, they would already be dead. Although the Prime Minister had attempted to kidnap them, it's never confirmed if he had wanted his sons dead; however, the twins consider her words to be true even after they had left their mother and had become adults.
Whether or not Mother Choi had genuinely loved her sons at some point in time or had only raised them into adolescents for blackmail material is unknown. However, she was hysterical when Saeyoung had disappeared to work for the intelligence agency.
She never physically appears in the game, but she likely has red hair and/or gold eyes like her two sons.
When he and Saeran still lived with her, Mother Choi would often send Saeyoung to run errands such as buying medicine, groceries, and alcohol for her. Like with his younger brother, Saeyoung was also abused by her, often being beaten and starved; however not as severely as Saeran was nor was he tied up.
Mother Choi abused him more because he was weaker and more sickly than his twin, Saeyoung. His punishments included having one of his legs tied to some part of the kitchen to prevent him from leaving as well as being beaten and being starved and dehydrated for days.
- In Saeyoung's Route, she committed suicide 2 years and 6 months before the Deep Routes.
- In Yoosung's Route, it was implied by Jaehee that she was killed by Saeran.
- In Ray's Route, she was killed by Rika in self defense.
- In South Korea, the Prime Minister and the President are two separate positions. The President is the head of state while the Prime Minister is appointed by the President and acts as a Vice President of sorts.