The Demon Prince

The emperor had no sons, only nine beautiful princesses, while his sworn brother had nine sons. Unfortunately, the two had made a pact to arrange marriages between their offspring, and all nine princesses were to marry into the royal family.
However, just as the wedding was approaching, bad news came from the Northern Territory: King Xiao Junlin and his eight sons had died on the battlefield. Only the ninth son, Xiao Xingyue, remained of the entire Xiao family. Due to his weak constitution, he was unable to go to war and thus escaped death.
On the day the Xiao family was in mourning, the nine princesses disregarded the dignity of a loyal and noble family and demanded to immediately annul the engagement and regain their freedom!
Faced with the nine princesses' aggressive demands, Xiao Xingyue, seeing through the royal conspiracy, tore up the marriage contract on the spot and announced to the capital: "His Majesty promised to marry the princesses to my Xiao family years ago. Although my brothers are dead, my Xiao family still has me, Xiao Xingyue. To prevent His Majesty from breaking his promise to the world, I am willing to marry the nine princesses and take care of His Majesty in his old age!"