Why’re are both coughing up blood? Plz spoil xx

Read this a while back so not 100% sure but Hazel made a contract with a demon. Using part of her life span I think she tried putting a curse or something on the empress. It was supposed to kill the empress, however, the empress was wearing that necklace thag tbe emperor gave her and that necklace helps protect the wearer from harm. So empress coughed up blood due tk the curse but did nkt die and Hazel coughed up blood because the curse did not work and so there was some sort of penalty.