Once, his grandfather Pu Hong teased him, "I heard that you, my blind boy, only shed tears from one eye; is that true?"
Pu Sheng responded, "That is fine; I'll just be like Shi Le [a slave who became founding emperor of Later Zhao]."
After his father (who had by then changed the family name from Pu to Fu) established Former Qin in 351, he was created the Prince of Huainan.
He also carried out cruel punishment—in addition to frequent executions, he also liked to cruelly treat animals—including throwing them into boiling water or skinning them alive, which he sometimes applied to humans.
In 357, the former Jin general Yao Xiang, who, after rebelling against Jin in 354, had intended to establish his independent state, attacked former Qin's northern territory, and the former Qin generals Deng Qiang and Fu Huangmei (苻黃眉) the Prince of Guangping fought back and captured and executed him.
His ladies in waiting leaked the news to Fu Jiān, who immediately led his private army to attack the palace.