Here is my theory- Liliana is the red haired childhood friend and she some kind of witch . She was in love with the emperor but the emperor was in love with the elf and she was jealous so out of jealousy she probably did some weird witchy juju thing which we will get to know later
okay hear me out i know this might be crazy but this chapter had the theorist in me going crazy So from what i get in this chapter Adan has a sister who seems to be fine according to doctors but has some sort of illness so now i've read enough manhwa to know that the MC is gonna somehow heal her (the sister), And we know Liliana (villainess) uses some sort of dark magic/ voodoo shit, Now if MC is second child of the empress what reason would Liliana (Villainess) have to kidnap MC there's no real benefit MC won't inherit the throne because she is a woman so why go after her? We also know that members of the imperial family are descendants of an elf so What if MC has some sort of power smth like divine power that can go against Liliana's (vilainess) dark magic or whatever power this would give her enough reason to want to kidnap MC and later on kill her
of course for your information this all just a theory i haven't read any spoilers
That suspicious red haired childhood friend of the emperor might've been part of the reason why he established that law which prohibits women to succeed the throne