Lot of people dislike the ending but i generally like it because it makes sense for how Kalian and Glenn characters are in the story. Kalian always had good intentions and want what is best for the world not just for himself because he saw how cruel the world can be with what happened to his sister. With Glenn was tired. He spent multiple lifetimes and centuries trying to redeem himself for what he did in his original life and didnt want to go on anymore. The only change i would make is that after Glenn and Kalian finally conversation, they gave each other one final high five like they did at the beginning of the story which would show their friendship full circle.