I don't see "The Cage" and "The Nest" as one. They are arcs where he was relevant so obviously they both matter for his development.
He caring about Yasratcha doesn't change anything that happened prior to that.
Unlike Yama I think that Doom himself was handled rather awkwardly. But I don't see why it felt forced to you there, their backstory explaining why they fought was fine.
Let's skip the Arc discussion, we are arguing about the emperors beard here.
Let's start with Yas - yes, it does. Greatly, in fact. It makes Yama a hypocrite. All talk, no action. Let me explain.
After it was revealed that Yama actually cares about his people, there were two people messing with his people. Excluding Paul and Doom, because they were pawns, that leaves Khell Helam and Yasratcha. Both of them fucked with his people. What did Yama do about it?
This dog.... all bark , no bite.
Yas was even worse, because at the end, Yama wanted him to survive and they had some kind of bromance.
Yas killed how many canines? He enslaved a lot of them, too.
Meaning that Yama's "development" actually wasn't a real one, because him caring for his people and defending/avenging them is just talk. Yas is living proof of that.
Doom and Paul are the only ones that messed with the hounds and faced consequences. Khell Helam and Yas did not face any at all (from Yama).
I, as his brother, would be really pissed about that fact alone......blood is thicker than water and stuff...yeah, right.
It is not a problem that they forgive each other. It is a problem how they do it. In such a small amount of time at that. It's unbelievable.
And the very same Yama that imprisoned HIS OWN BROTHER and banned the other, screams Yasratcha.....
That's my problem.