Records of the Three Kingdoms
Liu Ye, courtesy name Ziyang, was from Chengde in Huainan, a descendant of a son of Emperor Guangwu. He already had a name for planning in Yang Province and later joined Cao Cao. Before the Hanzhong campaigns he urged Cao Cao not to stop once Zhang Lu had surrendered, but to move on Shu at once. Cao Cao did not take the advice. Liu Bei then gained Fa Zheng, and the balance in Hanzhong changed.
Under Cao Pi and Cao Rui he still sat in confidential talks. He argued that Sun Quan’s submission could not be trusted, and he discussed whether to invade Shu. He could make a case on either side. Pei Songzhi quotes the Fuzi, which judges him severely for reading the ruler’s wishes. The biography says he died of illness near the end of Taihe. This page treats him as a Wei counselor and does not turn that note into the only fact.
Romance of the Three Kingdoms
In the novel Liu Ye is often at Cao Pi’s or Cao Rui’s elbow with one judgment: Sun Quan can be trusted, or he cannot, as the scene requires. He is never the subject of a chapter.
The book makes him a fluent courtier. It rarely spells out the advice he gave Cao Cao, in the Hanzhong year, to invade Shu.
Reference: Wikipedia · Liu Ye