Taking a hit for Naruto or Sakura, dying with honor during the war.
I have noticed something though, Ashura and Indra were brothers and everything was fine until Ashura would lead.
Hashirama and Madara were friends until the title of Hokage came into play and Hashirama was favored.
Naruto and Sasuke were best friends and always trying to top the other, and both want a shot at Hokage. If Sasuke dies after the war, it would be in a battle against Naruto for the title, but so will Naruto.
It seems only when the title is at stake do the souls of the brothers show up and force a fight that ends in death and destruction and a new cycle of hate.