As for Kisame, he is relatively neutral. Although Kisame is a rogue ninja, he is extremely loyal. As long as the faction he belongs to does not betray him, he will not betray that faction, even if it means death.
Nagato's betrayal of the Akatsuki Organization is an undeniable fact. The new leader, Uchiha Madara (Obito), is well-known and has never betrayed the Akatsuki Organization, which is why Kisame chooses to stay.
"Nagato betrayed us, despite all those things you did for him. As far as I know, if it wasn't for you healing him at the time, he would have died from overusing the Rinnegan."
Obito's fingers lightly tapped on the stone table.
"If you don't accept me as the leader, the position can be yours. In terms of qualifications, you're not inferior to anyone present."
Obito wasn't flattering. Just talking about capturing the tailed beasts, Su Xiao first captured one with Deidara and Sasori, then joined Itachi and Kisame's team, participating in many captures.
