Disclaimer; I do not own Naruto, however much I wish I did!
Naruto and Gaara woke up side-by-side butt-naked, to see Orochimaru and Kabuto hovering over them. They both shot murderous glares at their captors. But that was about all they could do, because both of them were numb. They couldn't feel anything at all.
"Ah." Said Orochimaru smiling, "Our guests are finally awake." His arms hung limply at his sides, blackened and dead. He grinned thoughtfully, his voice was as soft and deceptive as a snake crawling through the grass. "Oh, how rude of me, I'm sure you are curious to know why you are here. Well the truth of it is, I'm bored and I wanted something interesting to do. So you two have been brought here to entertain me." He was walking around the small medical room. "Kabuto and I have been developing a new jutsu, and I needed two demon hosts to test it out on. We are going to make you switch Biju with each other for a week. You will both be closely monitored of course. I am curious to see how you will both do. Before we begin boys, I want to let you know you know that if you spoil my fun, I will have to kill you the same way we brought you here, it took a lot of Kabuto's skill to keep you both alive. You were both out for nearly two weeks, hovering between life and death."
Kabuto looked over them both and added, "If you don't meet us back here at the end of the week, the demons will tear out of you in order to get back to it's original host and without me you'll both die! So be sure to meet us at the river, before 3:00 Monday afternoon."
"Shall we Kabuto?" Asked Orochimaru congenially, as though this was a casual social gathering of close friends, instead of one of his twisted experiments.
Kabuto grinned and began to gather chakra. He made a set of rapid hand signs and then slammed both of his hands into Naruto and Gaara's bare stomachs. A line of visible chakra cords connected them together and they watched as Nine-Tails and Shukaku were ripped clawing and snarling from the other's body, and was sent spinning into the chakra cord and then into the other boy's body. Kabuto then loosened the seals and seven symbols were locked onto the boys' stomachs.
Naruto and Gaara felt sick to their stomachs. Kabuto rolled them over to wretch in bed pans.
"Well, this is going to be such fun." Said Orochimaru brightly, unable to contain his glee at how successful this new jutsu was. "Tomorrow is Monday and you'll both be set free at your villages. Remember we'll be watching." He said smiling at them. "Well done Kabuto, we'll start off this evening."
This was an interesting idea that came to me in the middle of the night.
I think it'll be interesting to see how Naruto and Gaara handle each other's demons.