I'm dropping off the link to my Wincest Fic Masterpost.

Fics vary in lenght and rating, all spoilers and warnings are clearly posted on the entry header.  I hope you'll find something you like.

Title: The Stone That Rolls Downhill
Author:winddragon
Fandom: Supernatural
Characters/Pairings: Sam/Dean
Rating: NC-17
Summary: Sam didn't know where his life was going. He knew what he was good at, what he was bad at, and what he was great at that a seventeen-year-old shouldn't have any experience with. And he wasn't talking about hunting.
Notes/Warnings: Wincest. Dub-con, technically underage prostitution. ( Dub-con NOT between Sam and Dean.) Written for a friend and originally posted on my DeviantArt account.

Also a newbie here, so hoping my drabbles are adequate :D

Sam is careful, because it isn't always clean.

Title: How Quickly Things Unravel
Pairing: Sam/Dean
Rating: NC-17
Word Count: 5,897
Beta: I'm so grateful to lotrabc for looking this over for me, even though I had to coerce her to actually critique it! Haha.
Summary: Sam comes home from school with a problem and like Dean does with everything concerning Sam, he tries to help him solve it. But this might be one situation Dean doesn't quite have a handle on either.
Warning: Underage Sam is 14/Dean is 18, brother sex, penetration
Disclaimer: The boys do not belong to me, they're Kripke's but I like to think I know what has gone on between them.

Dean flips through the channels trying to find something good on the TV.

[we'll pull forever from its grave]
Sam/Dean -- adult
1841 words
warning: underage (Sam is 16)

Dean’s skin itches, feels tight, and his stomach aches with the want of Sam, the smell of his skin, the feel of it, the taste.

[we'll pull forever from its grave]
Sam/Dean -- adult
1841 words
warning: underage (Sam is 16)
notes: for lilibella.

( Dean’s skin itches, feels tight, and his stomach aches with the want of Sam, the smell of his skin, the feel of it, the taste. )

Title: Because You’re My Brother
Author: hysteria
Rating: NC-17
Pairing: Dean/Sam
Word Count: 1,664
Warnings: Underage, First Time, Incest, Angst, Hurt!Dean, Un-Beta'd
Summary: Dean wants Sam to be his first, Sam‘s not so sure. (AU young!Dean, older!Sam) Written for the supernatural kink meme.
Disclaimer: Don’t own Supernatural, or the characters involved.

fic here.