Why did the Eldest Princess sell out Yan Bingyun, the spy leader of the Qing Kingdom who was lurking in Northern Qi, to Northern Qi?

Eldest Princess Li Yunrui knew that Yan Bingyun was a spy because she couldn't find a clear answer in the search results provided.

The Eldest Princess didn't mention the specific clues that Yan Bingyun was a spy. However, according to the relevant documents, the Eldest Princess was suspected of betraying Yan Bingyun. In one conversation, she was questioned why Northern Qi had ordered Yan Bingyun's arrest not long after he was captured. This hinted that the Eldest Princess might be related to Zhuang Mohan, because not long after they had discussed learning in the palace, Northern Qi had received news of Yan Bingyun's arrest. However, this clue had not been fully verified, so it was impossible to determine how the Eldest Princess knew Yan Bingyun's true identity.

After Yan Bingyun returned to the Qing Kingdom, he became the Director of the Qing Overwatch Council and became the new King of Darkness. After Fan Xian returned to Jingdou, he had followed Fan Xian and helped him plan. In addition, the relationship between Yan Bingyun and Shen Wan 'er was also the most heart-wrenching existence in the drama. The specific follow-up plot was best understood by reading the original novel.

There was no clear information about the specific follow-up plot after Yan Bingyun returned to the Qing Kingdom. However, Yan Bingyun became the head of the Fourth Bureau of the Qing Overwatch Council, protecting the Qing Kingdom. He had helped Fan Xian come up with many ideas. After Fan Xian returned to Jingdou, he had become his little brother and had always followed Fan Xian. Yan Bingyun's position was difficult. On one hand, he was loyal to the Qing Kingdom and the Qing Emperor. On the other hand, he saw Fan Xian as a friend. He also had a relationship with the sister of Northern Qi who had instigated Shen Zhong, but the details of the subsequent plot and Yan Bingyun's ending did not provide clear information.

After Yan Bingyun returned to the Qing Kingdom, he became the head of the Fourth Bureau of the Qing Overwatch Council and took over his father's position. He took on the role of Director of the Overwatch Council in Qing Kingdom and became the new King of Darkness. Yan Bingyun had followed Fan Xian after he returned to Jingdou and helped him plan. His position was difficult. On one hand, he was loyal to the Qing Kingdom and the Qing Emperor. On the other hand, he saw Fan Xian as a friend. In addition, there was a heart-wrenching relationship between him and Shen Wan 'er. However, the specific follow-up plot and Yan Bingyun's ending did not provide clear information. Therefore, regarding the specific story of Yan Bingyun's return to Qing Kingdom, one needed to read the original novel Joy of Life to understand.

Yes, the eldest princess in Joy of Life was the princess of the Qing Kingdom.

The relationship between the Crown Prince and the Eldest Princess was complicated and dangerous. The Eldest Princess Li Yunrui was the Qing Emperor's younger sister and the Crown Prince's aunt. She had great financial power in the Qing Kingdom and controlled the palace treasury. The Eldest Princess supported the Crown Prince and hoped that he could succeed the throne. The Crown Prince was very dependent on the Eldest Princess and often sought her help and discussed matters with her. The Eldest Princess also had some feelings for the Crown Prince because she had provided help to the Crown Prince and there was no other woman by the Crown Prince's side to confide in. However, their relationship was discovered by the Qing Emperor. The Qing Emperor put the Eldest Princess under house arrest and prepared to abolish the Crown Prince. In the end, the Eldest Princess and the Crown Prince chose to commit suicide.

There was an affair between the Crown Prince of Qing Kingdom, Li Chengqian, and the Eldest Princess, Li Yunrui. The Eldest Princess supported the Crown Prince on the surface and secretly supported the Second Prince, Li Chengze. In the end, the Qing Emperor discovered their private affair through the exposure of a small eunuch, Hong Zhu. The relationship between the Eldest Princess and the Crown Prince in the drama was relatively shallow. The Emperor had already discovered it early on. In the end, the Eldest Princess took the initiative to reveal her relationship with the Crown Prince to the protagonist.

The Qing Kingdom's Eldest Princess ended up committing suicide. In Joy of Life, the Eldest Princess was sent to her fief, Xinyang, by the Qing Emperor because she had an affair with the enemy. She colluded with the Crown Prince and attempted to rebel and seize the throne, but the Qing Emperor was prepared and quelled the rebellion. The Eldest Princess knew that it was difficult to escape and chose to commit suicide. This ending was also in line with the setting of the Eldest Princess as the female villain in the novel.

The Qing Kingdom's Eldest Princess ended up committing suicide. In Joy of Life, the Eldest Princess was sent to her fief, Xinyang, by the Qing Emperor because she had an affair with the enemy. She colluded with the Crown Prince and attempted to rebel and seize the throne, but the Qing Emperor was prepared and quelled the rebellion. The Eldest Princess knew that it was difficult to escape and chose to commit suicide.