Your Army

[Antiga]

The castle where you can get the dwarfen wife will gets new units/spells/items when taking her as a wife. Same for the elven castle where the elven wife is located. I'm guessing it counts for Zombie rina and the demoness as well. Finishing certain quests enables you to buy units from places where you were unable to buy anything before.

If you're still in the starter area's and let the furious paladin live, killing him will spawn a different unit set(undead) at his store.