Read Seduce the Villain's Father Manhwa:
Upon opening my eyes after a bus accident, I found myself in the fantasy world of a webnovel I enjoyed reading... the only catch is, I reincarnated 20 years before the novel begins! Reborn as Princess Yerenica of the small Lebovny kingdom, Im determined to change the future in order to prevent the series of unfortunate events that will soon occur. In the original story, my older sister, Tejavia more.. , is pregnant with the future female lead, when she suddenly kidnapped by the Belgoat Empire emperor. But in my desperate attempts to protect her, I got kidnapped instead! And as if that wasnt bad enough, my body is ridiculously weak to magic. But... strangely enough, whenever Im by the emperor, I feel fine! The only way to save the emperor, who destined to die at the hands of his own son after marrying the villainess, and save myself from being afflicted by magic... is for us to marry! "Marry me, Father." "Father? Princess, I havent married yet, nor do I have any kids..."