Wang Chuzhi
At one point, Wang Chuzhi, then ruling Yiwu Circuit (義武, headquartered in modern Baoding) as its military governor ("Jiedushi"), commissioned his adoptive son Wang Du as the prefect of Yi Prefecture (易州, in modern Baoding). Wang Du invited Liu to serve on his staff as his secretary in military matters. Later, after Wang Du completed his term as the prefect of Yi — probably at the time that Wang Chuzhi commissioned Wang Du as the deputy military governor of Yiwu — Liu requested to leave governmental service. Instead, Wang Du invited him to go to Yiwu's capital Zhongshan () with Wang Du. At that time, Liu Xu's older brother Liu Xuan also arrived from Zhuo, and Wang Du recommended both of them to his father Wang Chuzhi. Wang Chuzhi commissioned Liu Xu as his secretary in headquarter matters, and shortly after promoted to him to be the secretary in Wang Chuzhi's role as governor (觀察使, "Guanchashi").