Sima Lun
When Emperor Hui's throne was usurped by Sima Lun the Prince of Zhao in 301, Sima Jiong the Prince of Qi (Emperor Hui's cousin) started a rebellion to restore Emperor Hui. Initially, Sima Yong sent his general Zhang Fang (張方) to support Sima Lun, but once he heard that Sima Jiong and his ally, Sima Ying the Prince of Chengdu (Emperor Hui's brother) had overwhelming force, he switched side and declared for the rebels. After Princes Jiong and Ying defeated and killed Sima Lun, Prince Jiong became regent and he, while angry at Sima Yong for initially supporting Sima Lun, nevertheless granted him additional honors as well as three of the nine bestowments.