She is the maid and he is the prince.
The legitimate daughter asked her to seduce him to make room for herself.
She went.
But the script didn't go as written by the legitimate daughter.
She made him remember her, care about her, and cannot live without her.
She helped him get over his stepmother's difficulties, settled the plot in the court, and took the position of Minister of War.
The legitimate daughter was so angry that she threw the cup, and the stepmother was so angry that she gritted her teeth.
But they couldn't move her.
Because he stood in front of her and said, "If you touch her, you touch me."
Later, the whole capital knew that Prince Xie, who was not a womanizer, doted on his wife, who was born as a maid.
Someone asked him why.
He said, "She taught me more than you will ever learn in a lifetime."