Yu Xun is Cao Cao's right-hand man. Cao Cao once commented on Yu Xun: "My ovary is also". This means that Yu Xun is to him what Sean was to Emperor Gaozu. However, Yu Xun devoted himself to the Han Dynasty, so when Cao Cao was a very important minister, Yu Xun could not accept it and eventually died of depression. Then the question is, why is Yu Xun, who is loyal to the Han Dynasty, willing to help Cao Cao? And finally, I don't want to find Liu Bei? The reason for this is the following：
At the end of the Eastern Han Dynasty, the eunuch group launched a fierce struggle with the consorts group headed by general He Jin. In order to destroy the eunuch clique, General blades listened to Yuan Shao's words, which later proved to be a super bad idea. The idea is to lead the west cool army into the city to deter the eunuch group, but who is the commander-in-chief of the west cool army at this time? It was Dong Zhuo, who had long had disloyal ambitions, and now it was a godsend, so Dong Zhuo entered the capital in a mighty way. When he arrived in the capital, he found that the blade had been seized by eunuch Zhang Rang, and he made full use of the interests of fishermen. So Dong Zhuo harmed the failed former emperor Liu Bian, changed Chen Liuwang and Liu Xie into emperors, and moved the capital to Chang 'an with the new emperor. All these practices are signs of disaster.
Cao Cao was very angry when he saw that the Han Dynasty was so shabby at this time. Dong Zhuo invited him, but he resolutely refused. When he arrived in Chenliu, Cao Cao kept a low profile and squandered all his wealth, formed an uprising army, raised troops in Chenliu and sent troops to crusade against Dong Zhuo. It can be seen from here that the early Cao Cao was also loyal to the Han Dynasty.
At the beginning of Liu Chen War, Cao Cao's influence was still very weak. Later, Cao Cao joined the 18th Route Warlord Alliance to jointly crusade against Dong Zhuo. However, these 18-route princes are actually heterogeneous. Among them, Cao Cao, that is, Sun Jian, who is really willing to fight against Xiliang Army, is fragile after all. The 18th route princes broke up in discord, and Cao Cao came out to develop independently. At this time, Cao Cao needs talents, and Cao Cao is very eager for talents. From Cao Cao's attitude towards Guan Yu, we can see that Cao Cao is a leader who cherishes talents very much. Basically, talented people have room to play under Cao Cao.
Besides, Cao Cao is a person who can help. Yu Xun was originally under Yuan Shao's account, but Yuan Shao was too narrow-minded to be a big deal. On the contrary, Cao Cao is a man who can achieve great things, and the gap between them can be seen from the 18 th Route Governors' crusade against Dong Zhuo. Yuan Shao was so fierce that he looked around and dared not March. Although Cao Cao was alone, he fought bravely on the battlefield. Once went deep into the hinterland of Dong, although he finally failed and almost lost his life, Cao Cao's courage and heroism were incomparable to Yuan Shao and others.
Many people are curious why Yu Xun, who was loyal to the Han Dynasty, helped Cao Cao instead of looking for Liu Bei. Because Cao Cao nominally represents the Han Dynasty, and Liu Bei is just a blank check. At this time, Cao Cao "held the emperor to make the princes". On the bright side, he represents the Han court, so following Cao Cao is working beside the emperor. On the contrary, although Liu Bei is under the banner of helping Han, Liu Bei has no influence. No territory, no army, no plan. Before Zhuge Liang came out of the mountain, Liu Bei took refuge in others everywhere and worked under their wings. He defected to his classmate Gongsun Zan, to Lu Bu, to Yuan Shao, and to Cao Cao, but he never had an acre of land. Except Guan Yu and Zhang Fei, there is no strength to compete with other princes, and there is no room for Yu Xun to display his talents.
Before Zhuge Liang went out to Nanyang to assist Liu Bei, Liu Bei stayed under Liu Biao's account and had no place of his own. Hosted in Xinye Town, the strength does not exceed 10,000. Before Battle of Red Cliffs, Liu Bei and Sun Quan joined hands. Most of the 20,000 troops provided by Liu Bei were borrowed by Liu Qi, and only a few of them were trained by themselves. Let's compare Liu Bei and Cao Cao before Zhuge Liang came out of the mountain in the twelfth year of Jian 'an:
Strength: Cao Cao destroyed Yuan Shao and pacified the north. His men claim to be thousands of soldiers, millions of soldiers. Liu Beibing has only 10,000, including Guan Yu, Zhang Fei and Zhao Yun. Most of the troops in front of Battle of Red Cliffs were borrowed by Liu Qi.
Territory: In the battle of Guandu, Cao Cao basically pacified the north. Before the 13th year of Jian 'an and Battle of Red Cliffs, except Liangzhou, Yangzhou, Jiaozhou and Yizhou, most of the thirteen states were in Cao Cao's hands, and only Liu Bei remained under Liu Biao's account. After Liu Biao died, Liu Chong surrendered to Cao Cao and Liu Bei had nowhere to go.
It can be said that before Zhuge Liang came out of the mountain, Liu Bei was a blank check. Obviously, Yu Xun won't join such a group without any strength, because he can't realize his ambition.
Liu Bei got Zhuge Liang in the twelfth year of Jian 'an, and his luck changed all at once. After Battle of Red Cliffs seized Jingzhou, Liu Bei entered Shu in the 16th year of Jian 'an. Slowly, he had his own territory and power. At this time, Cao Cao's ambition began to appear. Why didn't Yu Xun go to Liu Bei?
This may be because Yu Xun has his own ethics. Cao Cao and Liu Beidou have been fighting for so many years that they can't go to Liu Bei without Cao Cao. This is an act of betrayal, and Yu Xun doesn't want to. At this time, Liu Bei can't go, Sun Quan can't go, and he can't defect. Cao Cao's ambition expanded with his position, and he was no longer the master he had served, so Yu Xun, who was depressed, finally died strangely in the seventeenth year of Jian 'an. Some people say it was suicide, some people say that Cao Cao died of poisoned wine, and some people say that he died of depression. But none of this matters. The important thing is that he has no place in this world. The Cao Cao he has been following has changed. He is no longer the Cao Cao who serves the country. As his own character, he can't defect, Liu Bei can't leave, and Sun Quan can't leave, so he can only accept such a sad ending in the end.