Zhu Tao
It is not known when Zhu Kerong was born. His granduncle Zhu Ci and grandfather Zhu Tao had successively ruled Lulong Circuit from 772 until Zhu Tao's death in 785, upon which the Lulong soldiers supported Zhu Tao's cousin Liu Peng. Zhu Kerong's father Zhu Hui () remained at Lulong Circuit and appeared to have served as an officer under Liu Peng, Liu Peng's son Liu Ji, and grandson Liu Zong, as Zhu Hui was later referred to as a senior officer. Zhu Kerong, in his youth, also became an officer under Liu Zong.