I would like to point out that the Black Marsh faction cannot recruit spies or assassins, even after building a Dark Brotherhood Hideout. In fact, the only agent I've ever been able to make playing them has been the diplomat. Considering the lore it would only make sense that the Argonians should have good spying/assassinating capabilities rather than Shadowscales strictly being a unit in battles. Could someone possibly provide a fix that allows them to train agents from the DB Hideouts?