The one who stole her 'fiance' (AKA her sister) gets stuck with itching powder and ruins her face. The mean ex-fiance gets poisoned and suffers so much acute pain he's on the verge of death. The female lead sets up doctor's office/medicine shop and makes the ex-fiance pay her to cure him (via the emperor his dad) AND advertise her new shop through that 'task.' Then she sets it up later so the infatuated idiot dumps her sister publicly in her medicine shop as she's there to fix her face. Her face isn't fixed in the end.
In the original timeline, the main character died to save the Emperor. The Emperor was very sad because he was probably the only person who genuinely worried about him without ulterior motives (excepting his eunuch). Miraculously, the Emperor travels back in time before the incident (present timeline) and meets the main character again and due to some actions, realizing the main character has ALSO traveled back in time. Cue the massive overspoiling of the main character and romance.
Male lead is Li Min De (or his real name is Yuan Lie). They're not biologically related and are actually similar in age despite how young he looks early in the novel.
The female lead is Lin Xintong