Xu Shu 徐庶

In Chapter 35 of the Romance, on a night when Liu Bei is staying at Sima Hui's house, he overhears a man called Yuanzhi say that he went to see Liu Biao, found him to be a man of empty reputation, and left him a letter and came away. The next day, in the marketplace of Xinye, Liu Bei meets a man singing that heaven and earth are overturning and the great house is about to collapse; giving his name as Shan Fu of Yingshang, the man tests Liu Bei by advising him to give his horse Dilu to an enemy so that its curse would pass to him, and after confirming Liu Bei's benevolence he becomes his Military Adviser. Shan Fu defeats the troops of Lü Kuang and Lü Xiang with a plan that sends Guan Yu, Zhang Fei and Zhao Yun out in three separate forces. Romance, Ch. 35 §15–16 · 24–28 · 31–34

In Chapter 36, Shan Fu recognizes the Eight Gates Golden Lock Formation set up by Cao Ren and breaks it by having Zhao Yun enter through the Gate of Life in the southeast and exit to the west; he foresees Cao Ren's night raid and has Guan Yu seize Fancheng, which Cao Ren's army has left empty. Cao Cao learns from Cheng Yu that Shan Fu is Xu Shu of Yingchuan, who in his youth killed a man to avenge someone else, then changed his name and devoted himself to learning. Romance, Ch. 36 §1–2 · 4–6 · 8–10 · 13–14

Cheng Yu says that to summon Xu Shu, who is utterly devoted to his mother, they should bring his mother to them. Brought to Xuchang, Xu Shu's mother praises Liu Bei, denounces Cao Cao as a traitor to the Han, and strikes him with an inkstone. Cheng Yu keeps her alive, visits her daily, imitates the handwriting he obtains from her, forges a letter and sends it to Xinye. On receiving the letter, Xu Shu reveals his real name to Liu Bei and asks leave to go. Sun Qian urges Liu Bei to keep him, arguing that Cao Cao would then kill his mother and Xu Shu would strive with all his might for revenge, but Liu Bei rejects this as neither benevolent nor righteous. Romance, Ch. 36 §15–25

Liu Bei raises a cup at the Long Pavilion to see Xu Shu off, and Xu Shu says that even if Cao Cao presses him, he will not offer a single plan for the rest of his life. Xu Shu turns his horse back and returns to recommend Zhuge Liang of Longzhong, likening him to Lü Wang of the Zhou and Zhang Liang of the Han, and tells Liu Bei that the Hidden Dragon is none other than Zhuge Kongming. On his way, Xu Shu stops at Zhuge Liang's thatched cottage and asks him to help Liu Bei, but when Zhuge Liang, asking whether he means to make him a sacrificial victim, shakes his sleeves and goes inside, Xu Shu leaves for Xuchang in shame. Romance, Ch. 36 §26–27 · 31–35 · 37–38

In Chapter 37, when Xu Shu arrives in Xuchang, his mother rebukes him for being deceived by a forged letter and abandoning an enlightened master for darkness, then hangs herself from a beam. Xu Shu buries his mother on a slope south of Xuchang and observes mourning, accepting nothing that Cao Cao bestows. Sima Hui tells Liu Bei that Xu Shu's mother would never have summoned her son, so the letter must have been forged. Romance, Ch. 37 §1–5 · 8

In Chapter 39 Xu Shu warns Xiahou Dun not to underestimate Zhuge Liang and tells Cao Cao that he himself is a firefly while Zhuge Liang is the bright moon. In Chapter 41 he goes to Fancheng as Cao Cao's envoy, but instead of urging Liu Bei to surrender he advises him to leave the city quickly, and returns saying that though his mother's death has left him with lifelong grief, he will not devise plans. In Chapter 48 he recognizes Pang Tong, who has come to set up the chain-link plan, and, in return for not exposing the plan, learns a way to escape; after spreading a rumor that Ma Teng and Han Sui are attacking, he leaves with Zang Ba to guard San Pass. Romance, Ch. 39 §23–24Romance, Ch. 41 §3–6Romance, Ch. 48 §1–6