Short answers, pulled from the story.
Han Fei was a prince of the state of Han born with a severe stutter that rendered him unable to speak in court. He relied entirely on the power of the written word to influence the course of history despite his inability to speak face-to-face with kings.
Han Fei died in 233 BC after Li Si forced him to commit suicide by drinking poison. The Qin king regretted Han Fei's death shortly after the philosopher was killed for his perceived disloyalty to Qin.
King Ying Zheng of Qin read Han Fei's writings and declared that if he could make friends with this person he might die without regrets. The king went to war with the state of Han specifically to obtain an audience with the philosopher.
Han Fei's ideas continued to heavily influence every dynasty thereafter despite the Legalist school being officially vilified by the Han dynasty. The practical application of Han Fei's theories persisted beneath the surface of Confucian orthodoxy shaping the administrative machinery of China for millennia.
Modern scholarship has been open to the idea that a real Han Fei existed though Masayuki Sato considers it unlikely that all of Sima Qian's literal details of his life were historically accurate. Sinologist Goldin suggests that details of Han Fei's life were probably not far from the truth but that the specific events were less important for interpreting the Han Feizi than the ideas themselves.