Oh, and I'm going to say this now, there is a blanket ban on bashing Minato, Hiruzen, Danzo, Kushina, Hinata, Jiraiya or Tsunade.
For the first three, however, you can say that either, Minato could not understand hate, Hiruzen had to make sacrifices to keep Naruto safe in the long run and Danzo must be like a Bashed Dumbledore, believing that the end is worth the means to get there.
While in the Wave country, Naruto and Team 7 get into a massive fight, over whatever you choose (Your choice if Kakashi is involved).
The pain is too much for Naruto, and he runs off into the woods.
The beast, itself restrained by the seal from his father, cannot fight back The change manifests itself in several stages (You choose how their activated and space out)Stage 1; Increase in Chakra and physical abilities. Stage 2; Increase in intelligence, increased ability to learn Jutsu, begins to sense negative emotions Stage 3; Naruto's eyes become red permanetely.