The Emperor's Peerless, Wild Consort

[This is a one-on-one romance with no angst, so dive in without worry.] She was a genius assassin from the 21st century. After transmigrating, she became the unloved, useless legitimate daughter of the Prime Minister's household. He was the son of a divine lord from the Ninth Heaven of the Immortal Realm, powerful and cunning, with no one daring to cross him. Then he met her, and doted on her beyond measure. Anyone who hurt her would die. He was so possessive that even the sight of another man near her made him jealous... When the useless daughter meets the cunning Divine Lord, an enviable romance begins.