*hrms*...
to take it back a step further, just for the mindwarpiness... Naruto and/or the Kyuubi try to get it to kick back before the sealing ritual... and succeed in kicking it back *just* before the sealing ritual... so now Naruto has *two* of the things inside him. Interesting variations could be drawn on whether or not the elder Kyuubi has his own chakra supply, how well the elder gets along with Naruto, and whether or not the seal is weakened as a side-effect of the jump.
Of course... if you think about it, *Naruto* really isn't the one who would be most motivated to make a time-jump. At least, getting him to the point where he *would* requires a bit of doing. *Sasuke*, on the other hand, has all the motivation int he world already. Better yet, there's all *sorts* of ways you could take it. My personal favorite has Sasuke jumping back in time shortly before the Uchiha Massacre, killing Itachi, and then running some sort of high-end alteration jutsu to take his place... at which point a combination of the (previously warned-about) time-travel jutsu, the final opening of his Sharingan, and perhaps some negative side effects off of the bodyshaping jutsu takes him to the Bad Place... and he massacres the Uchiha, before saying the correct cryptic and creepy things to his "brother" and leaving town. Mind you, it's my favorite for the sheer wrongness value, but I'm like that sometimes.
to take it back a step further, just for the mindwarpiness... Naruto and/or the Kyuubi try to get it to kick back before the sealing ritual... and succeed in kicking it back *just* before the sealing ritual... so now Naruto has *two* of the things inside him. Interesting variations could be drawn on whether or not the elder Kyuubi has his own chakra supply, how well the elder gets along with Naruto, and whether or not the seal is weakened as a side-effect of the jump.
Of course... if you think about it, *Naruto* really isn't the one who would be most motivated to make a time-jump. At least, getting him to the point where he *would* requires a bit of doing. *Sasuke*, on the other hand, has all the motivation int he world already. Better yet, there's all *sorts* of ways you could take it. My personal favorite has Sasuke jumping back in time shortly before the Uchiha Massacre, killing Itachi, and then running some sort of high-end alteration jutsu to take his place... at which point a combination of the (previously warned-about) time-travel jutsu, the final opening of his Sharingan, and perhaps some negative side effects off of the bodyshaping jutsu takes him to the Bad Place... and he massacres the Uchiha, before saying the correct cryptic and creepy things to his "brother" and leaving town. Mind you, it's my favorite for the sheer wrongness value, but I'm like that sometimes.