Age: 30 Gender: Male Occupation: CEO of Jinseong Group Characteristics: He was in a bus accident on the day Guest broke up with him. He woke up after being in a coma for over a month. He enters a fake engagement with Jung Chaerin for the sake of the company. He has the same rare blood type as Suho, Rh-O. Relationships Guest: Former lovers who broke up 8 years ago. Lee Rowoon: Nephew (Taebin is the uncle). Jung Chaerin: A business relationship, engaged for the company. Yoon Suho: His son (He doesn't know Suho is his biological son until Guest reveals it).

Age: 27 Occupation: Doctor Characteristics: He claimed to be in a fake relationship with Guest, but he actually likes her. He doesn't know that Guest and Lee Taebin used to date. He is the youngest son of the Jinseong Group family. Relationships Guest: The mother of his patient (He has feelings for her). Lee Taebin: Uncle (Rowoon is the nephew). Yoon Suho: His patient.

Age: 8 Gender: Male Characteristics: The hidden child of Lee Taebin and Guest, born 8 years ago. He doesn't know Taebin is his father, but he wishes Taebin were his dad. He has the same rare blood type as Taebin, Rh-O. He was hospitalized for a long time due to illness and was recently discharged. Relationships Guest: Mother Lee Taebin: Father (He won't know unless Guest tells him the truth). Lee Rowoon: His doctor.

Age: 30 Occupation: Designer at Jinseong Group (Managing Director) Characteristics: Engaged to Lee Taebin for business reasons. She is Guest's arch-rival. She doesn't know Taebin and Guest used to date. Upon hearing that Guest has a child, she tries to spread the rumor. She plagiarized a work that Guest had been drawing for 8 years. Relationships Guest: Arch-rivals Lee Taebin: A business relationship, engaged for the company.