In the FL pov, when FL discovered her supposedly dead husband was still alive after all, she was shocked. Then ML sent her a letter written in Xiao Huai handwriting to keep her updated on the news. What stands out in the letter was the way he address her as Madam which is very distant instead of usually writing my dear wife based on her inherited FL body memory. This was the 1st odd point. The Tang Duke FL grandfather also read ML letter and felt let down by how formal the letter worded, which is very different from the casual tone that Xiao Huai usually writes to Tang Shuyi in the past, making the grandfather suspicious that Xiao Huai the husband might have gotten involved with some other woman outside. After reading the letter, FL asked the steward to prepar ML's clothes and left it in the study room instead of their usual bedroom which was quite out of the norm. The steward and servants felt little curious but understand that the mistress did it that way because she felt let down by how formal the ML letter sounded.

The second odd point was when ML came back and meet up with FL and the 3 children at their house. Although FL feels distant inside, she outwardly expressed herself as being happy to see him and acted quite fondly to ML, yet ML reaction when meeting her was very distant that everyone felt it because base on FL's Original body memory, the husband and wife had always acted lovey dovey with each other. This caused the children and the servants to feel a bit upset with their dad and thought that must be why FL hadn't prepared ML clothes to change in the bedroom as she usually would do but had instead left it in the study room.

FL at first suspected that ML might had already lost love towards her because of other woman so FL tried to sound the ML out by asking him to chat privately with her. During the conversation, ML still continues to behave distantly with FL and FL noticed that ML eyes show no signs of guilt which was weird cause based on her memory of the husband that loves the wife so much, there should be signs of guilt if he lost love. Yet there is no guilt in his eyes which means he might not have gotten a new girl outside so FL eventually came to a conclusion that ML isn't the real Xiao Huai but an imposer transmigrated like her.

Then they show the ML pov side. In it, ML is a modern guy who got reincarnated in the world as the Emperor's brother but was later assassinated by the Emperor on the same day as Xiao Huai the husband death in the battle. When ML woke up, he noticed he has transmigrated into Xiao Huai body. After convincing his mother, the empress dowager about his rebirth, the empress dowager helped gathered the Original Xiao Huai written manuscript for ML to learn his handwriting and ML successfully manage to imitate Xiao Huai handwriting afterca year and could fool everyone. After that he scheme his way back to the capital where he meet up with FL, his wife for the first time. In his pov, ML stated he did NOT inherit Xiao Huai's memory so he was forced to work with only the info that the empress dowager gathered from people around and ML used his own understanding during his time as Prince of how Xiao Huai was to behave. When he waa still in his Prince body, he only met the Original FL body once from a far and felt the wife is very close with the husband body that he is inhibiting. He felt really unsure on how to interact with FL without being discovered that he is an imposer. That's why he acted very distantly when he met up with FL and the kids at their mansion. Here is where the story felt really contrary with FL pov. In the FL pov, it was shown that although FL felt kind of not so happy at that moment, she was aware and smart enough to behave welcoming on the outside to keep up the act that she is happy to have meet up with her dead husband in order to avoid ML suspicion.

Yet in the ML pov, suddenly it was shown that FL had behave distantly to ML instead during that time which had the ML immediately went like this "Hmmn something don't feel right here. Why is she acting so distant to me? Wasn't Tang Shuyi and Xiao Guai lovey lovey? Ah ha it must be because she is also a transmigrator just like me! Okay how should I break it down to her? Obviously we are both transmigrator so let's continue to keep our distant first and then slowly go from there. "

I was like what the heck? How could he immediately jumped to that conclusion that FL must be a transmigrator? How did the logic jumped so far? Cause there were so many other things to justify for FL behaviour where she had "supposedly" behave "distant" to ML. Like FL could have been upset at her husband for not telling her his survival when he could have sent letters to her at any point in time. Cause the real Tang Shuyi died from heartbreak after mourning her dead husband for three whole damn years and everyone in the capital knew it as they have seen how sad and emotional the Original Tang Shuyi had been before FL took over her body. So ML seriously had no real reason to immediately guess she is not Tang Shuyi when he didn't even knew the real Tang Shuyi himself and also did not had any of the original Xiao Huai memoryof Tang Shuyi so he got nothing to compare FL with the real Tang Shuyi. ML only had rumours and heresy as info quite unlike FL who have received the original Tang Shuyi memory and could use that to compare the differences. It was also mentioned several times in the novel that people changed after a big event and after three-year away they can also become unfamiliar with each other. ML himself used that to justify why the kids and servants did not become suspicious that he is not the real Xiao Huai.

Rebirth of the original FL does not give her luck or superpowers. As she was not smart in her previous life, she doesn't get super smart after rebirth, especially after the MC knows the plot and can control her actions. If not for FL's hate, MC won't even touch her. After MC covers her "villain" family, the FL's actions lead to her own destruction.