Lengthy domestic (wincest) fics?
First time or established relationship are equally fine. Hell, it can even be gen provided the focus is on Sam and Dean's brotherly relationship and there are no other relationships (though Dean can still be a flirt, that's fine :P). The higher the word count the better.
While I'm not specifically looking for AUs, if you've got something in mind that otherwise fits the criteria I'd still consider it :).