The Tang Dynasty had such a prince, backed by empress Dowager Changsun, who was favored by Emperor Taizong of Tang, and also had his uncle Changsun Wuji, a great courtier, in the imperial court, but his position as crown prince was lost by him.
Li Shimin
As the eldest son of Emperor Taizong of Tang and Li Shimin, Li Chengqian was given high hopes as soon as he was born, and he became a prince at a young age. Li Shimin personally selected teachers for him and let him participate in the affairs of the government at the age of twelve.
Li Shimin
Unfortunately, Li Chengqian was weak and sick, and Li Shimin was distressed about his son and allowed him not to study more, but Li Chengqian studied harder and had the ability to govern the country at a young age. However, what was even more tragic was that Li Chengqian suffered from a foot disease, and as a prince, the teacher would often put pressure on him.
His psychology became sensitive and fragile, and he became more and more willful, first pampering the musicians, and then trying to kill the teachers who advised him. Because his younger brother Li Tai also wanted to be emperor, he mentioned it many times in front of Li Shimin, but because he loved Li Tai, he did not hold himself accountable. Li Chengqian was worried that the position of crown prince was not secure, and even had the idea of assassinating Li Tai.
Li Chengqian
Despite Li Chengqian's willful and foolish behavior, Li Shimin was reluctant to depose him as crown prince. However, Li Chengqian had the intention of plotting rebellion, and in the end he failed and was arrested, reducing Li Chengqian to a commoner and never being able to inherit the emperor's throne.