Sima Qian writes that a merchant bought a hostage prince the throne of Qin, then drank poison when the new king turned on him

Sima Qian's Records of the Grand Historian (Shiji), a Han-dynasty history, gives this account. Lü Buwei, a merchant of Yangdi, bought cheap, sold dear and piled up thousands in gold. In Handan he met Zichu, a Qin prince held hostage by the state of Zhao, and said: "This is a rare commodity worth holding." He gave Zichu 500 gold to win followers and spent another 500 on rare gifts for Lady Huayang, the childless favourite wife of Qin's crown prince. She asked to make Zichu her heir. Lü also gave Zichu a concubine from Handan. The Shiji says she hid that she was already pregnant, and she bore a son, Zheng. Zichu became King Zhuangxiang. Lü became chancellor and Marquis of Wenxin, with the revenue of 100,000 households in Luoyang. Zheng then became king. The Shiji says Lü placed a man named Lao Ai with the Queen Mother as a false eunuch. Lao Ai's faction was destroyed in 238 BC. In the tenth year of his reign the king dismissed Lü, wrote asking what merit or kinship he had with Qin, and ordered him and his family to Shu. Lü drank poison. Modern historians cited in a biographical dictionary of Chinese women treat the story that Lü was Zheng's father as a fabrication meant to question his legitimacy.