Chen Pingping knew the secret in the chest.

Chen Pingping was a eunuch. He had been a small eunuch in King Cheng's manor since he was young and had grown up with the heir of King Cheng (Qing Emperor). If Ye Qingmei had not appeared, Chen Pingping would have been a trusted eunuch by the Qing Emperor's side and not the Director of the Overwatch Council. Chen Pingping's original name was Chen Wuchang. When he entered the palace as a eunuch, he changed his name to Chen Pingping. He was about the same age as the Qing Emperor and had grown up together. The Qing Emperor trusted Chen Pingping very much. Ye Qingmei's appearance changed Chen Pingping's fate. He became Ye Qingmei's supporter. Chen Pingping was sent to monitor the son of King Cheng in the play, but he established a friendship with King Cheng. He became King Cheng's confidant and told him the reason why he became a eunuch. Chen Pingping was portrayed in the play as a person with deep feelings. He was full of respect and protection for Ye Qingmei. Thus, based on the information provided, it could be confirmed that Chen Pingping was a eunuch.

Fan Xian knew Chen Pingping. Chen Pingping was the Director of the Inspection Council. She knew Fan Xian very well and had given him a lot of help and support. Fan Xian treated Chen Pingping as one of the people closest to him. He had even been by her side during the diplomatic mission to Northern Qi. Chen Pingping also knew that Fan Xian was the Qing Emperor's son. All of her encounters with Fan Xian were within the Qing Emperor's arrangements and control. Chen Pingping's goal was to end the Qing Emperor's rule. She used Fan Xian to step into a power struggle and push him to go to Northern Qi to sort out the intelligence network. In short, there was a complicated relationship between Fan Xian and Chen Pingping. They understood each other and relied on each other.

Chen Pingping was a eunuch. Fan Xian and the Qing Emperor knew his true identity. Chen Pingping was revealed to be a eunuch in the play. He was a small eunuch in Prince Cheng's manor and grew up with the Qing Emperor (the heir of Prince Cheng). Only a few people knew Chen Pingping's true identity, including Fan Xian.

Fan Xian knew that Chen Pingping was a eunuch, and in the process of interacting with Chen Pingping, he gradually understood her true intentions and concern for him. Chen Pingping was the Director of the Inspection Council. He knew Fan Xian very well and had given him a lot of help and support. Fan Xian treated Chen Pingping as one of the people closest to him. He had even been by her side during the diplomatic mission to Northern Qi. Chen Pingping also knew that Fan Xian was the Qing Emperor's son. They had a special relationship. Fan Xian felt heartache over Chen Pingping's death and had a conflict with the Qing Emperor because of it. Chen Pingping's position in Fan Xian's heart was very important. He regarded her as one of his most important relatives.

Chen Pingping was a eunuch. This was confirmed in the search results provided. He had been a small eunuch in the Prince Cheng's manor since he was young and had grown up with the Qing Emperor (Prince Cheng's heir). Only a few people knew Chen Pingping's true identity, including Fan Xian. In the show, he provided help and protection to Fan Xian and taught him various skills. Thus, Fan Xian knew that Chen Pingping was a eunuch.

Yes, Fan Xian knew that Chen Pingping was a eunuch. Chen Pingping was revealed to be a eunuch in the play. He was a small eunuch in Prince Cheng's manor and grew up with the Qing Emperor (the heir of Prince Cheng). Only a few people knew Chen Pingping's true identity, including Fan Xian. Chen Pingping provided Fan Xian with help and protection, and taught him various skills. Thus, Fan Xian knew that Chen Pingping was a eunuch.

Yes, Fan Xian knew that Chen Pingping was a eunuch. Chen Pingping was revealed to be a eunuch in the play. He was a small eunuch in Prince Cheng's manor and grew up with the Qing Emperor (the heir of Prince Cheng). Only a few people knew Chen Pingping's true identity, including Fan Xian. Chen Pingping provided Fan Xian with help and protection, and taught him various skills. Thus, Fan Xian knew that Chen Pingping was a eunuch.

I'm not sure as the term'secret chest' is rather ambiguous without more context. It could potentially be a special box or container with a secret related to it in the context of the story.

Fan Xian was very sad when he learned of Chen Pingping's death. He cried bitterly and had never cried for anyone else. Chen Pingping's death caused Fan Xian and the Qing Emperor to fall out and became the fuse. When Fan Xian saved Chen Pingping, the Qing Emperor also stopped the people who went up to capture Fan Xian. He Zongwei also took the opportunity to slip away. Chen Pingping's death provoked Fan Xian and made him rise up against the Qing Emperor. Fan Xian's furious action made the Qing Emperor regret it for the rest of his life. Chen Pingping's death also let the Qing Emperor know that Fan Xian would definitely kill him, but he decided to let Chen Pingping go. Fan Xian's pain and anger caused him and the Qing Emperor to completely break off.

In " Celebrating Years," Fan Xian learned that Chen Pingping had died after he had been dismembered. Before Chen Pingping died, Fan Xian saved him and told him that Ye Qingmei's chest contained a long-range weapon. Chen Pingping smiled and said that he had also had this thing before he passed away. Fan Xian felt great grief over Chen Pingping's death. He cried bitterly. This was the first time he had cried for someone else. This showed that Fan Xian had only learned of Chen Pingping's death after his death.