"It’s in His Kiss" Book by Julia Quinn

The main charaters are Hyacinth and Gareth. Hyacinth is the eighth and final child of Violet Bridgerton. She is the last daughter, a fact her elder brother reminds her of, pointing out that she needs to marry. Hyacinth remains unmarried at the advanced age of 22. She is intelligent, independent, forthright and witty and full of life and doesn't hide that. No one quite like she - fiendishly smart, devilishly outspoken and according to Gareth, probably best in small doses. Still Hyacinth is stubborn and demands on participating in all their endeavors. But there’s something about her--something charming and vexing--that grabs Gareth and won’t quite let go. Gareth St. Clair, handsome, charming, intelligent and the grandson of Lady Danbury. He grew up trying to please his father. …