Walk with You

Both are historical mini dramas with the same leads as the main couple, and in both the ML is a prince and the FL has a secret.

They're sort of a gender flipped version of each other - one of the leads (ML vs. FL) has a strange curse/illness that makes them react to something and the other lead fixes them by letting them drink their blood.

+ both are historical short dramas
+ In Both, the FL is “infected by a phenomenon”
+ in both, blood plays an important role

In both dramas FL's family is massacred and she tries to clear their name. ML supports FL, and there is a blood bond between them. In The Rebirth FL is killed and reincarnated as somebody else, in Walk With You FL disguises herself as a maid.