Diplomatic action
As they were able to overcome their differences during the catastrophe that was the creation of the Flowing Peak, diplomatic relations were built between the intelligent trees and the fey. Many of them had saved the lives of members of the other or had been saved themselves and as such few wanted to continue the war.
As the trees still had a hard time adjusting to the chaos and whimsy the fey brought with them, there was still a need to protect their territory, however, the cooperation left little will to resume the war. As such several of the trees ventured into the fey lands in hopes of finding some sense of leadership they could talk to. They found this in the form of the Seelie court. This group of powerful fey were seemingly able to have some amount of control over the other fey in their presence. It was with these fey that the trees formed diplomatic relations. Although they had many differences in the end a treaty was created wherein a high-ranking member of the court would be stationed around the trees and make sure not too much whimsy happened. In return, the whimsy that this high-ranking fey would create would be tolerated and supported with resources as needed.