I recently read a short series of body swap fics. I'm like, 96.4% positive it was on fanfiction.net, but it may have been on AO3. It had a few onsets in the series, I think, and Bobby was in it to help out the boys. Dean and Sam were the ones that had switched, by the way. One of the fics in the series had Dean starting to get Sam's visions, and it hurt him a lot. This may not have been in the same series, but Dean, in Sam's body, had to do this fight-to-the-death thing with other "special powers" kids. They also got Dean out of the deal. I might be mixing up a couple of fics, but I'd really appreciate reading them again! Thanks in advance ☺

EDIT: FOUND!! Mileage series by Jennytork http://jennytork.livejournal.com/685519.html