I will admit I’ve not seen a single episode, but I rarely watch TV. All these recs were recc’ed to me by several friends on LJ. Still, two cute brothers, weird things going on and a cool car? I’m so catching the DVDs. Warning: Incest warnings ahoy! Squicky in real life but fictional? The forbidden can be yummy indeed.
Stuck to Me (Like Sugar to My Heart) Sam/Dean Underage m/m incest. Sammy gets drugged and develops a sudden need for, well, Dean. I mean, who can blame him? [NC-17]
In For A Penny-This is set in the Every Broken Thing ‘verse, only a few months after the flash back in Take it All Away, before they’ve got a routine down about this sort of thing. This places their ages at about twelve and sixteen for those playing at home. Underage M/M incest. [NC-17]
Reap What You Sow-Karma bites Dean in the butt. Repeatedly. [PG-13]. Humor, crack. Het! I’m intrigued by the author’s other SPN fics so keep your eyes peeled for more links 
Chapter 2.
To Everyone Who Thinks Sam Looks Like a Puppy: You Have No Fucking Idea, by Dean Winchester-PUPPY!Sam, literally. Crack. [PG-13]