A/N: Oh my Chuck! I'm so sorry for updating so long! I had a mild writer's block and a few problems at home but I wrote a long-ass chapter to compensate! please forgive me _

P.S. Anyway, this is an interesting chapter and I'm actually introducing a new Castiel persona called... (SPOILER!) Darkstiel.

Disclaimer: Carry on my wayward sooon, there will be peace when you are dooone, Eric Kripke, the WB and CW own Supernaturaaal, so cry some mooore.


Chapter Synopsis: The Winchesters finally learn Castiel's mission and the ugly truth behind the curse of the Mark of Cain. Same song, different verse but who's really playing the tune?


Chapter 3 – Come to the Dark Side, We Have Pie!

'How did I get here?' Was his first thought, and then, 'where am I?'

Everything was a mesh of distorted color. Wisps of blue and red chasing each other then fading out, some forming the palette of a rainbow, swirling to a slow hurricane. Tendrils of green and yellow lightly reached out to him, teasing, but shied away when he tried to make contact with them. He reveled in this curious world for what seemed like an eternity but then the scene before him slowly changed. There was a black dot in the center of his universe, spiraling ominously towards the bundle of colors. An obsidian hand reached out from the black hole, grasping at anything that passes near it. That Hand was an abomination. He wanted to get rid of it but found that he had no form, no body, to move with. He was just a color, like all the other colors around him.

The Hand finally found its prey, fingertips lightly brushing at an innocent blue wisp. Bright blue gradually turned to dark, then darker, then pure black. It became a thick dark smoke, bumping with other brilliant hues, infecting them with disease and corruption. Soon, everything would be swallowed by the darkness – including himself, but the tainted colors didn't move to consume him. They coalesced together, forming a pitch-black tunnel. There was light at the end of the make-shift tunnel and a person carefully stepped out from it. It seemed like the Hand manifested itself into a familiar face. The entity brushed non-existent lint off its dark pristine suit and looked at him. It regarded Castiel with an interested pair of red eyes. A deep glowing red, like the Mark.

"Like what you see?" It said in a disturbingly familiar growl. "This is what you will become. Not angel, human or demon. Not even god. Just… Darkness." He shivered as he finally realized it was the voice that spoke to him earlier. The entity cocked its head to the side, a mocking rendition of the angel's usual innocent quirk, "You think I'm the Mark of Cain? No, Castiel. I'm your deepest and darkest sin. I'm you." Its mouth morphed into a feral grin, "Welcome to the dark side."

"Cas? Hey! Snap out of it!" Castiel found himself whole and solid again, hands clutching the cold wooden table in the Bunker's library. Dean Winchester hovered above him, an anxious expression on his face. Sam was nowhere to be seen.

"Dean?"

The hunter heaved a lungful of air and expelled it in a rush, "Don't ever do that!" He lifted his hand off Cas' shoulder to snatch a bottle of beer and chug the contents down his throat. The angel swore no one was drinking anything when they sat down to talk. Observing more closely, Castiel counted four empty beers.

"Sam, Cas is back!"

Just like that, the younger Winchester came in bounding and looking harried. He was clutching several books and a Men of Letters folder; he dropped them all unceremoniously as he approached Castiel's sitting form. "Cas? Cas, you okay, man? What happened? You went catatonic for over an hour!"

"What?" Their feathered friend responded lamely, still disoriented and perturbed from his vision - if it could even be called like one. The brothers exchanged worried looks.

Sam eyed the red scar on the angel's forearm, looking stark and blood-like in contrast of Castiel's smooth white skin. He pulled out his chair and sat down heavily, glancing from his friend to his brother, "Dean was just finishing his side of the story when you got all rigid. Eyes glazed over, unmoving. You know, creepy stuff."

"We didn't know what to think at first. Maybe you were, I don't know, meditating? But 15 minutes in and we knew there was some real crap going on," Dean added, sighing. "So Sam and I went to do some research and came up nada." He glanced at the now-empty bottle in his hand, "Or tried to."

Castiel couldn't believe it. He knew it was coming but he was hoping for more time. The Mark of Cain was much powerful than he initially thought. "This isn't supposed to happen... not so soon."

Dean's head jerked up at his words, green eyes scrutinizing the angel's wide-eyed expression, "You know something, Cas?"

Castiel stared mutely at Dean, comparing his healthy features and the blinding brilliance of his soul from the hunter's future counterpart - whom the angel left behind in his old timeline. He remembered the Dean who wore the Mark, obeying the curse's whims. He remembered the Dean who murdered a kid and beaten his best friend to near-death. He remembered the Darkness and its purpose to destroy all of creation. Yes, the angel did know a lot of things. His father made sure of that. Chuck planted every memory, every thing related to them before and after the release of his sister. Some things that he never knew of and never even happened yet. Like Dean's deal with Death and Amara's bond to whoever wore the Mark. Lucifer possessing him. Castiel had to prevent all of those from happening - hopefully, with Sam and Dean's help. Though he prayed they wouldn't just make everything worse and he'd be forced to start from square one.

He turned to Sam. "We might need more drinks if I were to say anything more." Dean raised an amused eyebrow. Cas wasn't kidding.

"Go on, Sammy. Might as well end this nightmare with a bang."

Sam huffed and shook his head, getting up from the table. He went to the kitchen and retrieved three six packs. Might as well.


In the end, no one except Cas touched their beers. He was already in his third bottle when they decided to start discussing his other side of the story. Looking at his best friend, Dean couldn't shake off the feeling that the angel had changed. He looked better and worse than ever. As if something like that was possible. Castiel seemed confident and gave off a sort of focused atmosphere around him. If Dean was honest with himself, he'd say the Cas during the Apocalypse was back. Just without the stick up his ass... and more human. Though the hunter was glad that somehow Castiel was well and truly back, another goddamn problem just landed in their laps. He saw what the Mark did to his friend and couldn't stop worrying. Judging the fact that Cas was an angel, Dean would've never lasted long with the Mark of Cain on his arm. So he worried. Worried that he dodged the bullet and his best friend jumped the gun.

And knowing Cas, it was more than likely. He's always been a self-sacrificing idiot.

Sam cleared his throat to get both of their attentions, his full concentration directed on Cas' face. "So. The Mark of Cain?"

Dean unconsciously leaned closer, not wanting to miss a single thing. Cas took in a deep breath then clasped his hands together, blue eyes stubbornly trained downwards as if unraveling the mystery of alcohol and oak wood.

"The Mark is a curse. Lucifer originally had it and it didn't do much damage to him, except for bringing forth his genuine hatred for Humanity. Then came Cain, the first murderer. He killed his brother Abel and Lucifer passed the curse to him."

The brothers nodded at every word; they already knew as much. Castiel gritted his teeth before looking up at them. "But Cain was only human. He fell to the Mark's temptation, murdered countless souls for several eons. Nothing could kill him, not even Death himself. Finally, the Mark tainted his soul - bonded with it - and Cain became a Knight of Hell."

"A demon," Sam breathed out and gulped nervously, eyes straining not to look at the Mark. Cas nodded grimly. "Anyone who wears the Mark will go down that road eventually."

Dean abruptly stopped in his tracks, not fully understanding what his friend was saying. "What do you mean 'eventually'?"

Castiel visibly stiffened, pursing his lips and uncertainly flicking his eyes to the hunter's.

"Cas?"

Silence.

"Cas!" Dean said forcefully, almost yelling.

The angel turned his head away from the brothers' calculating gazes, blue eyes squinting at the offending dust on a bookshelf. He knew the older Winchester won't be happy with what he had to say. "The owner of the Mark will never die, Dean. Not truly. Even if the body dies, the person will be resurrected as a demon."

"But why?" The younger Winchester asked before his older brother could spout something inappropriate. Dean looked peeved. Sam shot him with a bitch face.

"Because... the Mark of Cain is a key. It's a key to a lock of the greatest evil."

Castiel gave them a few seconds to let the information sink in, not really knowing if they felt or understood the magnitude of his words. Dean, predictably, was just bullheaded as ever.

"You know what, Cas? I don't really care. I was there first and it should've been me. It's supposed to be my goddamn problem, not yours! So why the fuck did you take my place instead of hauling ass?"

"Dean..." his younger brother whispered harshly, warning him that he was going too far. They knew water was under the bridge, now, but they still didn't see eye to eye yet. Castiel and Dean both ignored him.

Cas growled low and angry, "Because you don't understand, Dean. You didn't understand what you were signing up for. What you could've done if I let you have the Mark-"

"I'm a big boy, Cas. I can handle my own mess!"

Dean knew he was acting like the biggest dick ever but he just couldn't let his best friend get away with all this penance and sacrificing thing without a word or two from him. And also the fact that even now, he still needed Cas to save him. He couldn't force the memories of Cas turning human and getting kicked out of the Bunker away. Just the thought of Castiel helping him rubbed him the wrong way. Maybe that was guilt and ego talking.

He was in Dean's face in a blink, expression thunderous and too blue eyes lightening up with barely restrained Grace. Cas never looked so ethereal and inhuman up close before. The hunter felt a bead of sweat trickle down the back of his neck. Two strong hands pulled at his shirt collar, almost knocking foreheads with the pissed off angel. "You couldn't handle your own mess, Dean," Castiel ground out. "You turned into the very thing we despise and I watched you slowly murder everyone around you. I watched and I couldn't do anything. It was all too late..." he trailed off, shaking Dean a little before dropping his hands and staring at him one more time. Cas broke contact first.

The older Winchester reached out uncertainly to grasp Cas' shoulder. His angelic friend stiffened at the touch but didn't say anything. Castiel's muscles were so wound together; Dean could practically feel the tension in his body.

"Cas? I'm sorry, buddy. I just - I'm worried and pissed you're stuck with that thing on your arm, man. What's really going on?" Dean didn't know what to think about Castiel's outburst. And his earlier fit of temper was just making him extremely guilty. His best friend didn't need anger issues on his already full plate.

Sam watched them carefully, conflicted emotions showing on his face. He was just as confused as Dean was but if what Cas said earlier was put into consideration, then they were all totally screwed. This might just be something that went beyond their pay grade.

"So, um, is there anything we can do about it?" He asked softly after a considerably long silence.

The cap from Cas' fourth beer made a popping sound as he casually twisted it off. He gulped loudly, tipping up the bottle until not a drop of liquid was found. Sam and Dean exchanged another worried look and an impressed one. Castiel distractedly wiped his mouth with the back of his sleeve. "I would warn you to not 'freak out'," he said using air quotes, "but that would just be contradictory."

"It can't be that bad, can it?" Dean muttered.

Sam cast him a sharp glare to shut up, "What're you telling us, Cas?"

"I'm telling you… that I'm the Castiel two years from now. I'm from the future."

The older Winchester's eyes bulged at that. "Holy-"

"-Crap," the younger one supplied.

"It's much worse than you think," Castiel stared at his lap, leaving the brothers in stupefied silence. "God personally sent me here to correct things. Or at least save us all from utter damnation."

"What? Uh, hol – hold on, did you just say god poofed you to two years from your original timeline? The big G-O-D?"

"Yes, and-"

"So Deadbeat Dad finally showed his ass? That's gold. Did he say 'sorry'?"

"Dean, that's not even the point here."

Their feathered friend glared daggers at them, apparently not appreciating their little commentary about his heavenly father. "Exactly. That's not the point. The point is why my father had to send me to this time – to clean up our mess," He glanced at Dean, "Your mess."

The older Winchester shifted uncomfortably in his seat, "Okay, shoot." Dean didn't really want to hear it though. He sensed whatever happened to Cas' timeline was largely a part of his 'punch first, ask questions later' policy. Sam looked like he's about to ask a million questions but held his tongue. Castiel gave them a measuring look before diving in.

"In my timeline, Cain succeeded in giving the Mark to Dean. You two also found the First Blade and killed Abaddon."

Sam stole a glance at his brother with eyebrows raised, then turned to the angel, "But...?"

"But things went downhill after that," Cas sighed. "Certain events led to Metatron uniting the angels and granting them safe passage back to Heaven. Metatron became their hero," he spat the last word, inciting curious looks from Sam and Dean, "and imprisoned me and Gadreel in the dungeons."

"Gadreel? Why was Gadreel with you?" The younger Winchester asked somewhat suspiciously. The last time Gadreel was with any of them, he possessed Sam and killed Kevin under Metatron's orders. Cas was even supposed to help him find the angel with the resonating Grace inside of him until Castiel disappeared, saying something about saving Dean.

Their feathered friend replied, "It seemed he was merely… feeling misunderstood. He wanted to be accepted again; take his honor back, and so I recruited him and he helped me find a doorway through Heaven. We were going to destroy the Angel Tablet but he sacrificed himself on the way."

Dean was skeptical. "You recruited the guy who murdered Kevin and he died for the good cause? Okay, judgments aside, you did destroy it, right?"

"Yes" the angel directly looked into Dean's eyes, voice cracking a bit as he said, "I did. Metatron found me but he was powerless. It was all too late though. I failed, Dean. I failed and I'm so sorry."

"What-?"

"Metatron killed you," Cas whispered brokenly. The Winchesters had to strain their necks to hear anything. "He lured you and he killed you, Dean. Sam was there with you and he had to see you die." He paused, and then took a shaky breath, "I'm sorry Sam, I couldn't protect him." It was the same words – the same apology – he said to Sam after coming back to the Bunker. It fell on deaf ears then, the younger hunter barely noticing him and murmuring the same words over and over again. Dean's gone. He's not here. Crowley took him.

Sam didn't know what to say. Dean dying and him being there was actually sickening, but Castiel apologizing to something he couldn't control was heartbreaking. He could only guess what his older brother was feeling at the moment. Dean looked as if he was rooted on the spot, staring at the angel in a mix of complicated emotions. But Cas plowed on, never giving the chance for the brothers to say anything.

"Sam… Sam, he took you home, placed you in your room… He tried to summon Crowley but he didn't show up. Sam didn't have to, actually, because Crowley was already there with you. He knew what would happen if you died, Dean, " Castiel looked down at his clenched fists. "He knew you'd become a demon."

The hunter wanted to puke his guts out. He wanted to puke everything that made up this fucked up situation, wanted to slap the daylights out of Sam for the expression of disgust and horror, and pity and anger on his face. Wanted for Cas to shut the hell up so he could just move on and forget everything that he heard tonight. But he knew the angel had to go on and Dean owed it to him that all those things weren't probably going to happen anymore - what with Castiel having the Mark of Cain instead of him. That fact didn't make anything better. It was just the other way around and Dean really felt like tearing his hair out.

"Was that – ," Dean cleared his throat, "was that the reason why you time traveled?" He glanced at the red Mark on Cas' forearm, "And crashing the party at Cain's?"

"It's part of it but there's more."

"Of course there is," Sam muttered. Dean just wanted this conversation to end. Now.

"You disappeared with Crowley and followed him in to Demon Territory. Sam eventually found you and brought you here to cure you with cleansed human blood. We managed to turn you back to human."

Dean thought that wasn't half bad, really. He spoke up, "Uh, well, that's good, right? But what happened with Metatron?" He was genuinely curious but also wanted to sidetrack the angel a bit from his impression of 'The Rise and Fall of Dean Winchester'.

Cas gave him a look but acquiesced. "The angels threw him in jail after his dirty work was revealed. He kept bargaining his release for my original Grace but..." He shrugged, "Yet Metatron came to earth twice. First by interrogation about the Mark and the second, Sam and I," Castiel glanced briefly at Sam, "took him from Heaven through some help and made him human. He led me to the Demon Tablet and what's left of my Grace, and... escaped."

"Dude. A newborn Metadouche slipped through your angelic defenses?"

"Shut up, Dean."

"Bitch."

"Jerk."

The angel was embarrassed to say the least but Sam's bitch face and Dean's offended expression made up for it. He almost smiled at their familiar banter but didn't, only gracing the brothers with an imperceptible quirk of his lips. "Metatron is quite older than me and much more knowledgeable." Cas' eyes darkened as he said, "But he wasn't knowledgeable enough on how to remove the Mark of Cain from its owner." Dean gulped. The talk was back on track.

"We needed to remove the Mark completely. Dean was showing signs of the curse acting up again but we couldn't find anything in the Men of Letters' accounts about it. Though there was something about a spell book called 'The Book of the Damned' that Cha-" Castiel almost slipped. He nervously eyed Sam and Dean's faces, relieved that they didn't catch the name. "that we found. It was an object of evil and abominations but Sam and I agreed to use it." He sighed, "Dean actually refused to use it because it was calling out to him - could feel the bond between the Mark of Cain and the Book."

The older Winchester scrunched his face at his younger brother and turned to Castiel. "Let me guess, you two went behind my back and it turned out to be a bad idea?"

Cas nodded. "Very, very bad. We found a witch, named Rowena - Crowley's mother - to help translate and find a spell to undo the curse using the Book of the Damned."

"Crowley has a mother?" Sam exclaimed. "I-I mean, of course he does, but... a witch? Seriously?"

"I bet she's as double-faced and power-hungry like her son," Dean snorted. "Man, I hate witches."

Castiel cast them a reprimanding look. They were getting distracted. "Yes. Yes she is. But she also succeeded in casting the spell. The Mark of Cain was taken off and Dean was free from becoming a demon again. Though by the doing that, we unknowingly unlocked the most evil entity in the entire universe - the Darkness."

"The Darkness?" Sam parroted.

"Before Light, there was Darkness," recited Cas. His too blue eyes looked far away, "The Darkness is god's sister and her name is Amara. She is destruction and destruction is her purpose. She kept obliterating god's works everytime he created something, so father locked her away - sealed her - for eons so he could make the world. Humans, plants, animals. Life. But she got out..."

Dean was tasting bile in the back of his mouth, "... and here you are." He looked pleadingly at Cas, "But why, Cas? Why couldn't god just take care of her? Why'd you have to come back here and shove yourself at the mess I made?"

"Because there is balance in everything, Dean. Without it, everything would cease to exist."

"Are you saying that if any of them disappears, the universe would too?"

"Yes, Sam. That's why by coming to the past, I had to take Dean's place in possessing the Mark so the balance would still remain. The space-time continuum is also sound. I altered the timeline and erased the older one by conjoining with my past self."

The older Winchester made an interested noise, "And I thought changing things in the past was taboo."

Castiel nodded, "I did too. Until god personally healed me and gave me bigger wings. He sent me here with all the knowledge that happened before and after the release of the Darkness. So I know most of everything that we should and shouldn't do to prevent that kind of catastrophe."

"Huh. That's kind of nice to hear, Cas, but we're worried about the Mark's effects on you. You sure we can't do anything about it? Dean said, chewing his bottom lip.

"Yeah, Cas. Do we even know what the Mark does to an angel?"

"I'm afraid I will... degrade to a darker version of myself, like Lucifer. I won't change quickly, give or take a year, maybe two." He hung his head in silent defeat, "I'm asking for your help here. Sam... Dean. Please, don't do anything reckless to free me from the Mark. I came here to save the world and I'm asking you to help me keep it from harm. If the day comes, when the day comes, I'll leave and you'll never see me again. But remember, I chose this." The angel rubbed the scar on his forearm briefly and nodded at the Winchesters, then disappeared in a flutter of wings.

The brothers didn't even had the time to register the shock of actually seeing an angel poof out of existence while they stared at each other. Each thinking if Cas would be back later or if he's gone for good. Dean was sure he'd be there by morning. The featherhead probably wanted some space and let them process things.

The silence after Castiel's words of promises and goodbyes hung at the Winchesters like the walk to a funeral. Sam was doing his hurt puppy dog face, opening and closing his mouth to say something but losing the nerve to come up with anything. Meanwhile, Dean just kept rubbing at his face, no doubt dying inside and too frustrated to look at anyone's face. His eyes were red-rimmed and faintly burning already. Damn Cas for leaving them to do nothing about it and damn Dean for acting so rash by going to Cain and everything that he did on Cas' original timeline.

Sam and Dean knew no one was sleeping that night. Maybe ever.


"No, no, no! Someone just messed with the timeline and it's making the Angel Tablet go crazy!" Metatron whined, scrambling from his office chair and holding up the tablet to Gadreel. "See this? It's glowing like a Christmas tree! I need to know who did this, Gadreel. I need to know where they got enough power to time travel."

The angel pursed his lips, looking thoughtful. "Is there a possibility that the Winchesters are behind this?

"Uh, no," Metatron snorted. "But I'm not dumb enough to cross them out. Okay, go on. Check them and report back as soon as possible. If it's not them, this means we've got a new player in town..."


So whatya guys think? I really really really wanna know! Please Read/Review/Fav/Follow. To be continued next time...