I second Brother Mine, and come bearing some more recs:

Gifts from an Apocalypse (http://sanshal.livejournal.com/8523.html) by sanshal has the Winchesters - mainly Dean - adopting Jesse the Antichrist from season 5. It's labeled Wincest, but honestly, it can be read as gen pretty easily.

Grey, Grey Mornings (http://spnflashfic.livejournal.com/42673.html) by legoline is a short gen story.

By Any Other Name (What Matters Is What Something Is) (http://thehighwaywoman.livejournal.com/24056.html) by thehighwaywoman is Wincest, but again, kind of easy to read as gen.