I give you my powers recs:
http://winchestergeneration.tumblr.com/powers

and my de-aged/ younger brother recs:
http://winchestergeneration.tumblr.com/de-aged

But unfortunately I don't think I have any that have both.

I did start one recently. I still need to finish the second chapter which is sort of a brief canon rewrite. Dean has powers in it, yeah. Their ages switched but so did their roles because of that.

http://archiveofourown.org/works/756016

Although, maybe I should make it (the second chapter) more...dialog-y than it is right now. Hm.

Edited 2013-04-29 01:31 pm (UTC)

I am just finishing up a very long fic that you've just described and requested and that is Do Dandelions Roar by kuwamiko: http://taybeck-fic.livejournal.com/12032.html

Summary: Two years ago Dean disappeared. Now John and Sam have gotten him back. But how will the three of them deal with the unexpected changes his trials in the time between have effected?
Warnings: Nongraphic references to non-con sex and underage prostitution. Violence. Language. Incest (duh).

Not a bad story, maybe you'll want to check it out? Though, Dean isn't born younger, he's deaged, and he has some sort of water powers instead of demonic... Also, there is Wincest. :P