Skyrim just needs more opposing factions that interact. It was so weird that each existed with their own little adversary, some tailor made nemesis that didn't exist to the rest of the world. In the Stormcloak city of Solitude, Penitus Occulatus Agents will return eternal and guard imperials that no longer exist. This is a great idea because it involves interacting with the Jarls and other factions, as well as delving into skyrim's sometimes stunted underbelly. Expansions to the underworld are always welcome.