Comment by Suraj Ahirwar (KIRITO) on The Knight King Who Returned with a God - Chapter 146

@Suraj Ahirwar (KIRITO) from what I understood their heart is being passed down to their descendants and the said heart belonged to the dragon called dragonia. It's a curse. It kills whoever posses it that's why u gotta pass it on but she made a deal which accelerated the process and now dragonia took over her body. (This is the best way I can explain I hope u understood))