Pass is the first. He already has a monarch, Liu Bei. They are sworn brothers. Instead of betraying Liu Bang, they turned to Cao Cao. Liu Guan and Zhang Taoyuan became sworn friends, which is a much-told story. Guan Yu has been with Liu Bei since the beginning of the war and is one of the leading figures of Liu Bei. In the battle of Xuzhou, Guan Yu guarded Pi and the two broke up. Liu Bei's life and death were uncertain, and Guan Yu was captured in Cao Ying. Guan Yu put righteousness first in his life. Faced with the uncertain life and death of his eldest brother Liu Bei, he naturally could not join Cao Ying, so he agreed with Cao Cao that he would join the Han Dynasty instead of Cao Ying. Once he heard from Liu Bei, he immediately went to find Liu Bei. So the affection between Guan Yu and Liu Bei is very deep from beginning to end. He will not abandon Liu Bei and surrender to Cao Ying.
Guan Yu ranks lower in Cao Cao's camp, but he has a position below one person and above ten thousand people in Liu Bei's camp. Guan Yu's martial arts skills are high, and he used to chop Hua Xiong with warm wine in the United States. Later, he helped Cao Cao chop Yan Liang and punish Wen Chou in Cao Cao's camp, so Guan Yu was extremely proud, and he also had proud capital. It is difficult for him to tolerate that people whose strength is not as good as his reputation are equal to or higher than him. In Liu Bei's camp, Guan Yu was the first to conquer the world with Liu Bei, under one person and above ten thousand people. If he had stayed in Cao Cao's position, Guan Yu would not have such a high position. Xia Houdun, Zhang Liao and Huang Xu were all generals who fought side by side with Cao Cao, and Guan Yu later joined in. His ranking is hard to surpass these people, which is intolerable by Guan Yu, so Guan Yu will not vote for Cao Cao's camp.
Guan Yu was loyal to the Han Dynasty, Cao Cao held the emperor to make the princes, and his ambition was obvious, while Liu Bei was in the name of reviving the Han Dynasty. Liu Bei is a descendant of the Han Dynasty. At the beginning of his business, Liu Bei always took the revival of the Han Dynasty as his responsibility. Guan Yu was also a supporter of the Han Dynasty. When he first came to Cao Cao's camp, Guan Yu showed that he was in the Han Dynasty, not Cao Cao's camp. Cao Cao is different. Although he welcomed the son of heaven back, he actually held the son of heaven as a vassal, and Guan Yu also understood this. Therefore, following his own morality, Guan Yu will not stay in Cao Cao's camp.
During Guan Yu's stay in Cao Cao's camp, Cao Cao did give him all kinds of preferential treatment. Even his favorite red hare was given to Guan Yu and worshipped as Hanshou Pavilion. In order to repay Cao Cao, Guan Yu beheaded Yan Liang and punished Wen Chou for him, but in the end Guan Yu resolutely left after hearing the news of his eldest brother Liu Bei, and Cao Cao finally failed to leave Guan Yu. Later, in Battle of Red Cliffs, Cao Cao lost Huarong Road and was stopped by Guan Yu. Guan Yu remembered the old love and let Cao Cao live.