Both MLs are FLs' stalkers who then move in with her or next door to her and try to protect her from someone else in her life.

While different time periods, both are historical dramas in which the ML is engaged or married to a cruel/unlikeable woman who then ends up replaced by an identical woman with a very different personality who he falls in love with. Both FLs have a matching jade token (either to each other or to the ML) and their switch/initial replacement was when they were young.

Both are a Republican Era setting in which the intelligent FL teams with the detective ML in order to solve a series of connected murders with a recurring symbol/style left behind at each crime.

Both are mini dramas involving one of the leads entering a dream-like world in order to help their health, with the other lead soon entering the world to help them.

Both are mini dramas involving one of the leads entering a dream-like world in order to help their mental health, with the other lead soon entering the world to help them.

Both are Republican Era mini dramas in which the leads are married and secretly leading a double life as spies or assassins, each believing the other is not involved in their profession.

Both are Republican Era mini dramas in which the leads are assassins who are hiding their job from each other.

Both are mini dramas with rival assassins who marry each other, with each unaware of the other's secret identity.

Both are mini dramas with rival assassins who fall in love and marry each other, each unaware of the other's secret life.

Both are historical dramas in which the FLs have their faces exchanged with another woman. Both MLs are generals and first met the FL when she had her original face.

Both are historical dramas in which the FLs are betrayed, seemingly killed, and have their faces changed by a man who finds them injured and saves them.

Both are historical mini dramas in which the FL swaps faces with another woman and returns for revenge against those who wronged her.