After Reading the Book, I Used Earthy Love Words to Guide the Blackening Immortal King

On my first day as a vicious female supporting character in the world of cultivation, the system asked me to say earthy love words to the blackened male protagonist to extend my life. I attacked hard, but the base of his ears turned red and he couldn't hold the sword steady. Where is the cold-blooded killer that we promised? Now he waits for me to flirt with him every day with a cold face, but the darkening value does not move at all - I am almost driven crazy by the system!