Su Qingyuan (modern identity: the country's top agent + field medical expert, codename "Yuan", proficient in fighting, poison production and detoxification, medical skills, disguise, intelligence analysis, strategic planning, strong execution ability, calm and sinister, ruthless in protecting shortcomings, but gentle and soft-hearted to the male protagonist)
Time travel identity: The eldest daughter of the Prime Minister's Palace of the Dayao Dynasty. Her biological mother died young, her father was cold and eccentric, and her stepmother Liu was framed. She was raised in the remote Suiyuxuan since she was a child. She was weak, stupid, and powerless. She was bullied by her concubine and looked down upon by her servants. The original owner was pushed into the water and died of starvation and freezing. The heroine's soul traveled through her body and took over her body.
Xiao Jue (titled King Ji, the youngest son of the late emperor, and the younger brother of the current emperor) was extremely talented but had no cure for strange poisons since he was a child. His body was in decline, plagued by cold poison, and he was bedridden all year round. His temperament was aloof, taciturn, and violent. He is alienated, does not trust anyone, his power is secretive, and there are forces of dead men secretly. He is feared by the court and the harem. Everyone thinks that he is about to die. Only the heroine can detoxify him and warm his heart.)
