Both FLs swap places with the SFL in an arranged marriage, resulting in them meeting and falling in love with the ML.

Both couples break up and the FL doesn't tell the ML she's pregnant. Years later, the two reunite, with the ML learning he has a young son. Both MLs have a chronic health condition that their child has inherited.

Both MLs are chronically ill. Both FLs become pregnant by the ML, then end up trapped in the palace by the emperor who is obsessively in love with them.

Both are historical mini dramas in which the leads have a romantic past connection but now seem to be on opposite sides, with the ML hiding his identity and appearing to be cruel toward the FL while still in love with her. Both FLs stab the ML at least once due to misunderstandings.

Both are wuxia/historical dramas with either a BL or a censored BL relationship between the leads, one of whom has an abusive, controlling father who treats him as a weapon, and who is hiding his true identity from the other lead.

Both MLs are formally humans who were turned into monsters against their will, searching for the one who turned them a century or more later. Both FLs have very difficult lives but are strong characters. Both dramas have beautiful cinematography and feel like a dark fairytale.

Both are historical dramas in which the ML is turned into a vampire and later on meets the human FL.

Both are Republican Era mini dramas with Leo Yang as the ML and a FL whose plot for revenge causes her to cross paths with the ML.

Both are Republican Era mini dramas where the FL hides her identity and enters a household in order to get revenge.

Both are Republican Era mini dramas where the FL hides her identity and enters a household in order to get revenge.

Both are Republican Era mini dramas where the FL hides her identity and enters a household in order to get revenge.

Both are Republican Era mini dramas where the FL hides her identity and enters a household in order to get revenge.