Would not it be nice if your fortress / castle would not always appear as dead. Initially, that's no big deal you're busy with resource extraction and lift your troops but once the fortress wall and that all buildings were built, you've reached the populationcap. It feels dead to me.
You have your bond-slaves to gather your the Ressoucen, but there is no real town life.
So why not depending on size, fame, security, etc. people start to live in your Town and pay taxes for it. An option for town festivals.
An actual market with items for population and heroes -> no more endless potions for units and heroes, they can use they've bought.
A tavern for npc heroes who brag about their feats and drown their loot. After that they leave town for more adventure if lucky the will return -> they do their buisness without you doing anything as long as you provide for em making your fortress even more famous and rich of course.
If your homeland really is safe place noble or rich merchants could start to live there and add various bonuses
enough of it - i hate google translator it works a ****