Since When Were You the Villain?

Sophia got transported into a book without even knowing what a novel is. Then, one day, she got into a contract marriage. ‘Killian’ was a perfect Northern Duke with black hair, red eyes, and a handsome face. So, Sophia believed without a doubt that he would be the male protagonist. But…
“Ah, I got caught.”
The smell of blood. Killian’s eyes narrowed. She realized he was the villain while his cold hand caressed her cheek.
“There won’t be a breakup, Sophia.”
Raising the corners of his lips slightly, he whispered softly. ‘I think this is also a cliché… that I hate!’

(Source: KakaoPage, translated)