I Took My Sister's Place as the Tyrant's Bride, and He Spoiled Me Rotten

Everyone says that Xiao Yan, the Prince of Zhenbei, is cold-blooded and bloodthirsty, ruthless in battle. All three of his previous princess consorts met gruesome deaths. Ye Qing, an illegitimate daughter, was forced to marry him in place of her elder half-sister Ye Ying, who was pregnant and had refused the marriage. Ye Qing went into the marriage expecting to die, but after entering the prince's estate, she became the object of Xiao Yan's doting affection. When Ye Qing was heavily pregnant, Ye Ying had a change of heart and plotted to harm her younger sister and take her place as princess consort.