Why does Tohru become a bad guy in the last three episodes of Jackie Chan Adventures?

In the last three episodes of "Jackie Chan Adventures," Tohru becomes a "bad guy" due to a magical transformation that occurs when he is influenced by the Dark Hand and the power of the enchanted talismans. This shift in his character leads him to momentarily ally with the antagonists, showcasing the struggle between good and evil within him. However, Tohru ultimately redeems himself by overcoming this dark influence and rejoining Jackie and his friends in their fight against evil.