The Rule of Three was a Nihil policy that involved the splitting of proceeds from the marauders' operations. The Eye of the Nihil—Asgar Ro, and later his son, Marchion—also received a share of the payouts from jobs that utilized the Paths that the Ros provided according to the Rule of Three.
The structure of three Tempest Runners and one Eye was designed so the Runners would have too great a rivalry with each-other to unite against the Eye. Similarly, each Tempest of the Nihil had their Storms under the Runner who could in theory unite to overthrow their Tempest Runner, but were too mutually quarreling in practice to mount a successful insurrection. Following the Battle of Kur, Ro managed to unite all of the Nihil under his command.