What are the co-op rewards?

[Twosteps]

The articles online are not very clear on this, and I'm seeking some clarity. I know there is no "progression" for the person who joins your game, which is fine to me. But do they still earn "souls" so they can level up their character? Articles talk about coins, but they make it sound like its something you can spend on buffs or something.

[Dasginosis]

Souls reward is 1/3 of host.