So I wrote this thing. It's a little OC for Sam, but I'm gonna chalk his dickish behavior up to the demon blood and leave it at that. Takes place at the end of 4x20 "The Rapture". Bit of a backstory for this tidbit, towards the beginning of that 4 month grey area between s3 and s4, maybe one or two weeks after Dean bit it, Shay left Sam and took off on her own. Couldn't stand the reminders any longer and flew the coop, leaving him wide open for Ruby's influence.

Shay stood in the light rain, watching as the Novak's taillights disappeared in the distance. Her arms were crossed tightly over her chest as she forced herself not think about what she'd seen Sam do to that demon.

God, Sam… demon blood? You're drinking…

Deep down inside the huntress knew that, had it not been for Sammy being her little brother, she probably would've put him down on the spot, no questions asked. No human would dare drink demon blood, only a monster would stoop so low.

This is all my fault, Shay rationed, if I hadn't left him after Dean went to Hell, he would've never gotten to this point… this is on me. My baby brother's become a fucking monster because of me. Tears burned at her eyelids, yearning for escape but she blinked them away, he told me to look out for Sam and I tucked tail and ran the first chance I got…

"Shay?" a warm calloused hand came down on her shoulder, and she flinched away from the unexpected touch violently. The huntress turned to look at the culprit with wide wet green eyes, filled with the seething thoughts flowing through her mind in that moment. Sam bit his lip and looked down at the ground.

There was dried smear of blood on his neck and a tinge slightly hidden underneath his lower lip. Shay looked away, "what is it?"

"Dean's ready to go."

"I'll find my own way," she responded, inflectionless, "you guys can go on ahead."

"Shay—"

"Sam, don't." Shay spat, glaring at the ground, "just don't, okay? I'm not in the state of mind to ride in the same car as you, so just leave it at that and leave me the hell alone. Dean might be okay with pretending like that," she waved a violent hand towards the warehouse, "didn't just happen but I'm not."

"So you're just gonna ignore it? Is that it?" Sam sneered, "you and Dean are just alike, it's almost like both of you went down under and came up wrong."

"What the hell do you want from me?" Shay snarled in response, "You want me to get pissed, to punch you, to scream about how embarrassed and disappointed I am in you? Because that's barely a blip on the radar compared to how fucking awful I feel about my part in this bullshit!"

Sam blinked in disbelief, "Shay, I chose this, you didn't make me—"

"I didn't?" the blonde huntress laughed mirthlessly, "oh, sweetheart, I might as well have giftwrapped you and handed you over to that demonic slut the moment I decided to leave you. But what the fucking hell, it's not like I can go back and tell myself to stay. What's done is done, and you're… you're…"

"I'm what, Shay?" Sam responded, faint traces of irritation seeping back into his tone, "what am I?"

"Deep down inside you already know the answer to that," Shay replied softly, "I can see it in your eyes."

"You don't know anything, Shay," the younger Winchester muttered venomously, "you have no idea, hell, you don't even have a real part in the apocalypse. At least Dean's got that much going for him. Where do you fit in all this?"

Shay snorted derisively, ignoring the small spark of pain in her chest, "so what, you're proud to be a part of this whole apocalyptic scheme? To be a fucking pawn in this mess?" she looked incredulously at her younger sibling, unable to believe what she'd heard, "Forgive me for not feeling too hurt that I'm not a glorified bitch for either side of the game board. Because that's what you and Dean are, but at least Dean doesn't have any delusions of grandeur about it. A bitch is a bitch, Sam, doesn't matter how you spin—"

"HEY!" Dean interrupted what was rapidly devolving into a verbal bloodbath, "how 'bout you two stow that shit so we can get the hell outta here? We don't have time for this."

"Like fucking hell," Shay stalked off, "I'll find my own way to Sioux Falls." She wasn't a stranger to grand theft auto, she'd be fine. Sooner she got back to South Dakota, the sooner she could get in her 'Stang and get the hell out of dodge. There weren't enough adjectives to describe how done she was with everything remotely apocalypse related.

Why bother sticking around where I'm not needed? It's not like I'm a necessary piece to this puzzle…

"Shay, c'mon," Dean's voice called out behind her, "we can ride back together."

"I said I'll find my own way, Dean," she snapped in response, "just leave me alone." The tears she'd been fighting to keep at bay spilled over in that moment, but she forced herself to keep walking, back straight and head held high. A large part of her wanted to find a car and never stop driving… but, regardless of what her dumbass brother had to say, she did have a part to play and, if the past had taught her anything, it was that running away didn't solve a damn thing.

I found myself pretty annoyed at Sam while I was writing this little tizzy, which is nothing new because season 4 Sam always grinds my gears, apparently demon blood makes you act like a dick, but if anyone was wondering why he was getting torn a new one, there's your reason.