Venethan had never been content. Even now, when he was fairy king and sometimes had access to beings with seemingly unlimited magical power, he wasn't satisfied. He wanted more.
He didn't get another chance to go to the demon realm before Zarath came back, which was for the best since he had no idea where his tiny faction was truly hiding out. He claimed a fairy wouldn't be able to reach it anyway so he would have to be teleported in. The tunnels were too small for someone with wings to fit.
The demon promised to periodically check the cave where he kept his boat on the shoreline closest to his hideout. Venethan could come whenever he was able that way.
With that arrangement, they spent the next two years continuing their collaboration to the best of their abilities. He became the de facto ambassador to the demons, which was ridiculous knowing his diplomatic capabilities, but Azariel had other things to do and no other fairy volunteered for the job.