The first thing you can know is that Li Yu is the sixth child of Emperor Li Jing of the Tang Dynasty. His uncle Li Jingsui and his brother Li Hongji are above him, so he can't be emperor. Li Jing and Li Jingsui are both sons of Lie Zu in Southern Tang Dynasty. After Li Jue proclaimed himself emperor in the Southern Tang Dynasty, Li Jing was named Crown Prince. After the death of Li Jue in the Southern Tang Dynasty, Li Jing proclaimed himself emperor, known as Yuan Zong of Emperor Taizong. Li Jing swore before his father's coffin that his brothers would inherit the throne from generation to generation, so he renamed his younger brother Li Jingsui King Qi and his son Li Hongji King Nanchang. Later, Li Jingshui was divided into Huang Taidi by Li Jing, which was equivalent to the Chu army. However, Li Jingshui obviously did not want to sit in this position and was very uneasy for several years. He repeatedly proposed not to change Chu Jun's position on Wang Jin.
However, Li Hongji, the eldest son of Li Jing, did not become a prince at first, but he had great ambitions and thought that Li Jing had robbed him of his status as a prince. Although Li Hongji is taciturn, he has high military ability. When the enemy invaded, he didn't run away, and finally cut off the enemy's head in a deadly battle. The war also made Li Hongji a prince, but the first thing Li Hongji did after he became a prince was to poison his uncle Li Jingsui. After this incident, Li Hongji's status as a prince was abolished. From then on, Li Jing gradually noticed Li Yu. Although Li Yu claimed to be Zhong Yin at this time and didn't want to be the emperor, Li Yu was still named the prince and ranked in the East Palace.
It can be said that Li Yu took the wrong throne, but he also became a rare emperor with no achievements in history. Perhaps being an emperor is not his initial intention, he just wants to be a literary poet.