Right now, vassals spawn as gia structures on the map randomly at the start of a match. they can be captured and then become player controlled, once captured they activate their ai, produce workers and a patrolling army, and then produce a small fighting force to attack your enemies. This does mean you can technicaly control their units, but the basic ai implemented will order them back after, usually within 5 seconds of you giving their units orders. This is a vassal i captured, and as you can see its harvesting basic resources and its army is patrolling its territory.   Ideally once i have more time im looking into having these spawn as seperate players once captured, they can still use this basic ai i have in place but it would stop players from acidently selecitng their units. 

Done: Arsenal Houses (A to D) Storehouse Barracks Forge Market Fortress Hall    

thanks @LordTriggers! Interesting concept! Here are a few question to better understand: Vassals will belong to gaia initially, I presume, so will not be friendly.Trying to capture therefore means first killing their army and then capturing their CC, but wouldn't they just belong to the conquering player's territory?  Or will they stay kind of "allied"? Can anyone else captrure them after you had done that already, i.e. if you don't watch out, they might be allied with your opponent again? Looks like they deliver their resources to their owner (which would be normal after capturing their CC). Will their stats count in the players stats (e.g. with respect to population cap)? Sorry for the ignorant questions, just trying to get a grip on your concept.

Cool!

I'm currently working on vassals, small randomly placed settlements on the map that will auto produce their own workers to gather resources in the area as well as a small patrolling army to gaurd their own territory. The player can capture these vassals in order to have them autonomously work for them. Vassals can provide income for their owners using their workers as well as add a basic level of defense for an area with their patroling army, after they have all their workers and a defending army, they will slowly build up a small army to attack your enemies with.   I find it adds some really cool and valuable points on the map to take control of. While they wont be able to defeat your enemies on their own, coordinating your attacks with theirs can add a welcome boost to your own attacks. This also makes the maps feel alot more dynamic.