Xu Shu

Xu Shu (180 – 230s), courtesy name Yuanzhi, originally named Xu Fu, was a Chinese politician of the state of Cao Wei during the Three Kingdoms period of China. He was born in the late Eastern Han dynasty and used to be a vigilante swordsman in his early life. However, after running into trouble with the authorities, he renounced his old ways and took up scholarly pursuits. He lived a reclusive life from the 190s to mid-200s in Jing Province (covering present-day Hubei and Hunan provinces), where he met and befriended Zhuge Liang. In late 207, he became an adviser to the warlord Liu Bei and served under Liu for about a year. He also recommended Zhuge Liang to Liu Bei during this period of time. In late 208, Liu Bei was defeated at the Battle of Changban by his rival Cao Cao. Xu Shu's mother was captured by Cao Cao's forces during the battle. Feeling lost and without a sense of direction, Xu Shu eventually left Liu Bei and joined Cao Cao. He continued serving in the state of Cao Wei – founded by Cao Cao's son and successor, Cao Pi, who ended the Eastern Han dynasty – and died of illness in office.

Xu Shu's defection from Liu Bei to Cao Cao was fictionalised in the historical novel ''Romance of the Three Kingdoms''. In the novel, he was Liu Bei's chief strategist before Zhuge Liang came along, and he once helped Liu Bei repel two attacks from Cao Cao's general Cao Ren. He was eventually tricked into leaving Liu Bei and joining Cao Cao, but he recommended Zhuge Liang to Liu Bei before leaving and swore never to give advice to Cao Cao. Provided by Wikipedia