For me .epi. 27 is confirmation that the empress was the mastermind.It was revealed that she was a widow. Why would an emperor marry a widow? Furthermore , she has the power to grant a high rank to 5th uncle when he requested a reward for writing a hymn for her dead husband. Therefore she has wealth and power that she can do anything she likes without fear from the emperor.Drama dropped this clue for its similarity to Duke Jing, who married for rank, wealth and power. The Emperor also married her for that. Another clue dropped was by Prince Qing, who said SH 's situation was similar to his. Parallel of 1 family with 2 sons, where 1 parent wanted 1 son to have everything and will do anything to get rid of the other son. Song family, father wanted SH to be Duke and will do anything to get rid of SM. Royal family, mother wanted PQ to be emperor, and will do anything to get rid of CP.
Female centric drama and women power. This director is good at making his drama unique.Commonly, others will have women as CEO in their businesses. There is business but that is a sideshow. The important focus is : women drive the plot. 1 woman can change her mate's fate with her life's skill of calm,calculated,analytical assessment and medical skills- FL. Another woman was a catalyst to break up a happy family- FL stepmother. Last woman can control her husband and the country-empress.
Am more interested to find out why they were reborn?Theory 1- the stranger who said he was the writer of Book of Truth and guided FL on how to change fate, he's god? He was to correct their mistakes in their past life ? ML and FL were to be married for their fate to blossom. 2ML was to be a monk for his fate to blossom. Is 2ML also reborn? Yes, that would explain him as that monk handing over the Book of Truth to FL. 2nd- significantly given a magnifying glass. Einstein Time Theory used mirrors.He was the issue that rebirth was initiated. In Buddhism, 7 lifetimes to achieve nirvana.Abbot had said he has initially no emotion and no attachment at his core.In past life, he became a monk because of bad outcome from being a court official. In the present ,he still has ego for wanting to be famous and has attachment to FL.2nd grave sin he committed in the past was helping PQ to become emperor,son of Heaven, PQ was unworthy. High possibility if he helped PQ to become emperor again,not only will he not continue path to nirvana but will fall to hell.
2nd Theory - writer got trapped in a game setting/his novel and has to get the desired result to get out.