From UESP: "Taskmaster, is the Daedric Prince whose sphere is the ordering of the lowest orders of Oblivion"
Could this mean he was initially one of Jyg's underlings, tasked with bringing order to parts of Oblivion, but then rose into the status of Daedric Prince after? I mean, it doesn't make much sense how Jyg is the Prince of Order, and yet Peryite also holds order in high esteem (he even says "may order be in your life" or something to that effect to the PC IIRC).