As Tuoba Si grew, he was said to be a wise and kind young man, whose actions were all in accordance with proper protocol. In contrast, his oldest younger brother Tuoba Shao (拓拔紹) was a frivolous and violent young man, and often received punishment from Emperor Daowu, and Tuoba Si tried to correct his brother's behavior by rebukes, but this made Tuoba Shao angry at him. In 403, Tuoba Gui, by this point emperor (as Emperor Daowu), created him the Prince of Qi. In 409, Emperor Daowu was intent on creating Tuoba Si crown prince, but based on the Tuoba tradition that when an heir is decided upon, his mother must be put to death, Emperor Daowu forced Consort Liu to commit suicide. Either before or after he did so, he summoned Tuoba Si to explain to him that this tradition was also in accordance with Emperor Wu of Han's rationale to put his favorite concubine, Consort Zhao (Emperor Zhao of Han's mother) to death, to avoid overly great maternal influence on a young emperor. After Tuoba Si left his father's presence, because of the affection that he had for his mother, he mourned greatly. Hearing this, Emperor Daowu summoned him back to the palace—and, because Emperor Daowu, in his late reign, often displayed great paranoid and violent tendencies, the new crown prince's attendants suggested that he not go to the palace but hide in the country. Tuoba Si agreed and did so, fleeing the capital Pingcheng, where Emperor Daowu had moved the capital in 398.