4Game

The first Dverger we meet, Haldor accepts coins and treasure, meaning that the Dvergers do have an understanding of currency and value it to some degree

So it would only make sense that you can hire them by giving them treasure. This would supplement as a taming mechanic for them, because lore wise taming them like other mobs doesn't make sense

Each treasure item (coins, amber, pearls and rubies) could be assigned as the "taming" item for each type of dverger (rouge, fire, ice and support) It should work similar to how taming in Minecraft works, where each dverger has a non specified amount of treasure they take to be hired. Once they're hired you can set them to follow you or stay, and hold on to items in their own inventory.

You could also "learn" their names once they are hired to distinguish them from other dvergers. And they could have a time meter for how long they are hired for, so you'd have to replenish it with treasure if you wanted to keep them on your team.

This would be an awesome way for solo players to simulate a co op experience as the game gets more difficult in future biomes.

For balance, it could be tied to a "Communication" skill that raises the more lore stones/boss stones you find and read, and that skill determines how many treasure items on average it take to hire them, how long they stay hired, how much inventory space they have, etc.