李承乾
After Li Chengqian was arrested, Li Tai visited Emperor Taizong everyday, and Emperor Taizong promised to create him crown prince—an idea that was also suggested by the officials Cen Wenben and Liu Ji. However, Zhangsun Wuji suggested that Li Zhi, also favored by Emperor Taizong, be created crown prince. In order to persuade Emperor Taizong to create him crown prince, Li Tai told Emperor Taizong that he would agree to kill his own son and make Li Zhi crown prince should he be allowed to inherit the throne. However, the statement backfired, as Chu Suiliang pointed out that the statement could not possibly be an honest one, and that in effect, there was the potential that, if Li Tai were created crown prince, the situation between Li Chengqian and Li Tai might repeat itself. Li Tai, meanwhile, made comments to Li Zhi that he should be worried in light of his friendship with Li Yuanchang—comments that Li Zhi told Emperor Taizong, who then began regretting promising Li Tai the crown prince position. Further, when Emperor Taizong visited Li Chengqian to rebuke him, Li Chengqian accused Li Tai of machinations against him, causing him to plot treason. Depressed over the actions of Li Chengqian, Li Tai, Li You, and Li Yuanchang, Emperor Taizong summoned Zhangsun, Fang Xuanling, Li Shiji, and Chu to a private meeting, during which he told them his intent to create Li Zhi crown prince instead. Later that day, when Li Tai tried to enter the palace to visit Emperor Taizong. Emperor Taizong put him under house arrest, and the next day created Li Zhi crown prince.