[4] During the reign of Emperor Yuanzong, he became the Grand Guardian of Li Yu, who was heir apparent to the throne.
As Grand Guardian, Xu successfully proposed the construction of a "clear mind pavilion", from which imperial commands would be relayed, on the palace grounds at Jinling.
[8] Xu is mentioned in a fictitious tale collected in A Record of Ghosts and the Living, in which he dreams of a "an emissary dressed in black" who informs him that he will "become Lord of the Northern Dipper".
[9] He is also told in his dream that Chen Kangbo (陳康伯) will be his vice-magistrate; both men die concurrently a year later.
[10] Xu You is portrayed by Beijing actor Gao Yuqing in the 2005 Chinese historical drama How Much Sorrow Do You Have.