The prototype of the story is true. The protagonists are Song Renzong as a baby, his biological mother Li Chenfei, his adoptive mother Liu E and his biological father Song Zhenzong. Song Renzong is indeed Song Zhenzong's own flesh and blood. But Song Renzong's biological mother is not Liu E, but Li Chenfei.

The truth is that the emperor and queen found a maid-in-waiting surrogate. But at that time, there was no test tube technology, and the maid-in-waiting went into battle in person. As a result, the maid-in-waiting accidentally gave birth to Song Renzong.

"Civet cats for princes" is a literary story in the classic "Three Heroes and Five Righteousnesses". When telling the story of Song Zhenzong, Liu Fei conspired with Guo Huai, the internal supervisor, to exchange skinned civet cats for babies born in Li Chenfei, and Li Chenfei was put in limbo.

After Zhao Heng's death, Injong Zhao Zhen acceded to the throne, and Bao Zheng went to Chen Zhou to investigate the fraud case of his uncle Pang Yu's relief fund. On the way, Bao Zheng accepted Li Fei's unjust case, rehabilitated himself, and ushered in the story of Li Fei's return to Korea. Because the story is a household name, it is told by later generations. However, "civet cats for princes" is fictitious, and the relationship between Liu and Injong is not the same in history.

According to the records in History of Song Dynasty and History as a Mirror, Liu was from Huayang, the capital of Xichuan Road. His parents died when he was young. After marrying Gong Mei, a silversmith, he went to Bianjing to make a living and met Zhao Heng, then a prince. Although Liu was favored by others, they were forced to separate because of their birth and remarriage. It was not until he acceded to the throne that Liu Cai was welcomed back to the palace.

But at this time, Liu was too old to have children, so the maid Li (that is) gave birth to a son Zhao Benefit for Zhenzong (later renamed), while Zhenzong claimed to be born by Liu and entrusted the young Zhao Benefit to Liu's care. However, it was not until Liu's downfall that Injong knew that his biological mother was.