i think when pain fights naruto .. pain `ll tell him that he is weak as jiraiya
and naruto `ll be like *WTF* then pain `ll tell him about how he killed jiraiya..
and naruto `ll turn 2 the kyuubi ..more than 4 tails.. and destroy everything,. and then sasuke come and activate the mangekyou 2 control the kyuubi power 2 make naruto calm down.. and both of them fight pain and kill him ^_^