Disclaimer: I do not own Supernatural, Dean, or Castiel. If I did, I would not be freaking out about the finale since I would know what's going to happen.

Companion story to "Sorry's Not Good Enough."

Not Strong Enough

It pounded through his veins like a war drum, thrumming in time to his heartbeat. Kill! Kill! Kill! The song of the Mark had been unleashed, but Dean had no desire to stop it. After all, the Stynes were monsters. They had killed Charlie.

They deserved what had happened to him. Even that kid would have turned out like them, so he had to die. Dean was just doing his job.

So then, why was Castiel looking at him like that?

"I took down a monster." He looked down to make sure the safety on his gun was on. "Because that's what I do. And I'll continue to do that," Dean shrugged finding that he couldn't look at Cas over by the kid's corpse, "until – "

"Until you become the monster." Cas straightened and looked him in the eye, and he seemed almost disappointed in him. That pissed Dean off. After all, who was the angel to look at him like that?

Dean looked him right in the eye. "You can leave now, Cas." He turned, meaning to leave himself. There was nothing for him here anyway, though the Mark continued to pulse, wanting more blood.

"No." He heard Castiel walking closer. "I can't. Because I'm your friend."

The wave of anger wasn't really surprising. Cas was his friend? What sort of excuse was that? Within Dean's mind, images from all of those times Cas had let him down surged through in instant replay. A heat began to build in his heart. Charlie had been Cas's friend, too. Sam and Cas had been sneaking around behind his back, and they had dragged Charlie into this. Now, she was dead.

So it was Cas's fault just as much as the Stynes' that she was dead.

"Really?" He turned back towards him. "So let me ask you something." He walked closer, and he could see that Cas was wary but somehow still trusted him. Dean felt an inexplicable need to hit him, to do something to him. "Do you screw over all your friends?" He couldn't help but ask, since Dean's life had only gotten worse ever since this angel had pulled him out of hell and stepped into his life.

"Sam and I were trying to cure you. We still are." Cas defended his eyes never wavering from Dean's. The fury rose higher in Dean's chest. They were still continuing even after he had told Sam to shut it down? How could they do this?

"Like hell." Dean growled.

"We can read the Book now." The slight hope that was in Cas's eyes disgusted Dean. He couldn't believe they were still going through with this. He was perfectly fine; he didn't need to be cured of it when he could still fight it. There wasn't any point in this.

"Oh, so what?" He couldn't help but ask. "So you might find a spell that might take this crap of my arm?

Cas shifted, looking slightly uncomfortable. Dean knew that he knew it was a slight chance. Still, it wasn't enough to persuade him to stop it seemed.

"And even if you do, what's it going to cost? 'Cause magic like that does not come free." He didn't notice how his voice was getting lower, almost threatening with the menace it contained. "No, it comes with a price that you pay in blood." Dean searched the angel's face to see if he got it. "So thanks, but I'm good."

He turned to leave once more, feeling that he had gotten his point across. He was fine despite all of Sam and Cas's worries. Why couldn't they see that?

He felt a bit of shock run down his shoulder as Cas reached out to stop him. "No." The angel came around to face him. "You're not." Dean glanced down at the hand on his shoulder, but looked up as it was removed.

Castiel stood before him, his eyes filled with truth, worry, and something else. However, his words fell from his lips ringing with conviction. "Maybe you could fight the Mark for years, maybe centuries as Cain did." His eyebrows lifted, showing how unlikely he thought that scenario was. "But you cannot fight it forever."

Somewhere, in a distant part of Dean's mind that wasn't bathing in blood and fiery rage, there was a voice saying that Cas was right. It said that he was already losing this battle against the Mark. Dean shoved that voice down and tried to drown it in the rest of his mind.

"And when you finally turn, and you will turn." Truth was still leaking from Cas's voice. Not like the angel could tell a decent lie in the first place, but Dean knew that Cas at least thought this was the truth. "Sam, everyone you know, everyone you love, they could be long dead." His eyes never left Dean's. "Everyone except me."

For a moment, Dean wanted to laugh at that statement, even though it didn't fit the serious atmosphere in the room. After all, Cas had died just as much as any Winchester, and he really thought he would live that long?

Still, something in Dean became unsettled at that thought and he had to look away from Castiel's sincere gaze.

"I'm the one who will have to watch as you murder the world." His head tilted as he tried to make his own point. "So it there's even a small chance that we can save you, I won't let you walk out of this room."

Dean finally identified everything in the angel's eyes. His eyes contained his conviction, his worry, and his sorrow and love for having to someday bear witness to all of this. It managed to calm the flames within for a moment, but then they began anew with a new rage as the words fully sunk in.

Castiel had no intention of killing him if it got bad. He was going to break the promise that Dean had admittedly partially forced and tricked out of him in that restaurant before things started getting bad. The angel was going to betray him again, and the world would suffer for it.

Dean couldn't believe it, but he did know that if he didn't leave there right now, he would have to hurt Cas. It wasn't about just Charlie anymore as Castiel's betrayal, due to his faith in Dean, hurt and enraged him even further. And he seriously doubted that Cas would be able to stop him.

After all, Cas wasn't an enemy.

Right?

"Oh, you think you have a choice?" He asked, wanting to leave.

"I think that the Mark is changing you." The worry was most prominent in Cas's eyes.

"You're wrong." Dean didn't notice how monotone his voice had gotten, even as his hands were curling into fists. He just knew that he had to leave. He had to kill something, so he had to find the next monster.

"Am I?" Cas tilted his head a bit, narrowing his eyes. "Because the Dean Winchester I know would never have murdered that kid." He nodded at the Styne kid on the ground.

Murder? That was such a weird word for Castiel to use as Dean looked at the kid himself. He hadn't murdered anyone; he had just killed a monster.

That small part of him suddenly threw a memory of him of a different Dean from a different future. One that had killed others without mercy or hesitation. He had been an all-around, cold-hearted dick bag, and Dean had vowed to never become like him.

And he wasn't. He only took out threats, so there was no way that the Mark was controlling him. The Mark actually made him more powerful to fight the monsters, so there was no point in getting rid of it. Besides, before the Mark he had always been whining and dragging Cas and Sam into his messes. He wouldn't do that anymore, so why couldn't they just drop this whole thing?

"Yeah, well," Dean turned back to Cas, "that Dean's always been kind of a dick." He moved to walk around Cas and leave, but the angel stopped him once more by putting his hand on his shoulder.

"Dean." And now Cas sounded somewhat desperate, pleading. "I don't want to have to hurt you." His eyes were also asking him to stay so they could work this out together.

Well, maybe they should have thought of that in the first place.

"I don't think that's going to be a problem." Dean said, finally meeting Cas's eyes directly.

The angel looked somewhat confused, but it quickly faded as Dean reached up and broke Cas's arm, following it with a punch to the face.

Dean relished it for a moment. He remembered the last time he had punched the angel in Zachariah's Green Room. The angel hadn't even flinched and Dean had pulled away with a smarting hand.

Now, bones crunched under his hand and flesh gave way as his fist met the angel's face.

Cas's arm dropped and he brought up his other hand. "Dean." His voice was garbled a bit as blood ran out of his mouth.

Dean ignored him as he punched him again and again. The angel could just barely defend himself as he landed blow up a blow, following it up with a knee to his gut. He tossed the angel over to the pile of books that the Stynes had intended to burn.

He turned, thinking he could finally leave when there was a shuffling sound and a faint, "Dean." He continued to walk until it was followed by, "Stop." Turning, he could see Castiel had staggered to his feet. Blood trickled form his mouth and nose, but his eyes were still pleading.

That was it. Dean had given him every chance, but this was too much. Castiel was practically asking for it.

Dean walked forward, like a lion stalking it prey. He punched Cas in the face, but Castiel used the momentum to try to place Dean in the gripping hug that he had used already several times in the past to restrain him. Dean solved that quickly by back-head-butting the angel. His grip came loose, and Dean easily escaped.

As Cas was bringing his hands up to clutch what was probably a broken nose, Dean took advantage of it by kneeing him and shoving him into the table.

Castiel didn't even try to put up a fight as he was repeatedly slammed into the table, both his ribs breaking and blood streaming from the wounds he received on his face. Dean didn't know if that was because he didn't want to hurt him or he was too weak, but either way, it was pissing Dean off.

The angel fell to the floor. Dean crouched down to turn him over, and noticed as he did so that Cas's angel blade was falling out of his sleeve. He easily picked it up, flipping it to hold it by its hilt. He roughly grabbed Cas's tie and hauled him up slightly, the blade pointed at his heart.

This was almost too easy. Castiel had made the mistake long ago about trusting Dean and now he would finally pay for it. Blood covered Cas's face as he looked up at Dean, eyes hazy but never leaving his face. Dean prepared to stab him, making him pay for everything he had ever done to him.

Suddenly, Cas's hand came up, the arm that Dean had broken. It clutched at Dean's wrist. "Dean." The word was choked and muffled. Blood dripped out and ran down his chin. "Please." Despite his tone, which was hurt, there was an acceptance in his eyes.

Whatever Dean chose, Castiel would accept it.

It struck Dean. He was pleading. Some part of Dean froze. There had been only one other time that Castiel had pleaded at him. At that time, Castiel had been convinced that he was helping and that he was fine and things were right. He had been wrong though. Now, he was pleading once more. Was it possible that he was right this time though?

Another image came to Dean: Castiel, under the control of Naomi, pounding into Dean, leaving his face bloody and his arm broken. As he had later learned, Cas had been fighting against her orders the entire time, even though she had trained him for this express purpose. Dean had pleaded then, and told him that they had needed him. It had been the final push to help Castiel overcome her control and he had dropped the blade.

Words also whispered across his mind. And then you'd kill the angel Castiel, now that one, that I suspect would hurt something awful.

This rushed through his mind, but in reality only a few seconds passed as Dean studied Cas. The angel blade trembled in his hand as the Mark continued calling for the blood of the angel.

Without another moment of hesitation, he brought the blade up and slammed it down.

Silence reigned for a second.

Dean stood up and stepped away, looking down at the angel's body.

Castiel's eyes, which had closed at some point, opened and his head moved slightly. He was looking at the angel blade, which Dean had stabbed into a book laying not even three inches away.

Dean turned his back on Cas, finally making his way to the front door. He found that he couldn't look at Castiel, at what he did. He ignored the angel's blood on his hands and the Mark's disappointed cries.

"You and Sam stay the hell away from me." He gruffly said. Dean almost looked back, but he didn't fully turn to the angel. "Next time, I won't miss."

And with that, he left the angel, Cas, lying on the floor. His friend, his almost something, his angel was lying there broken and bleeding. And most of Dean did not care.

That small part of him was appalled at what he had done, at what he had almost done. It screamed at him of how he could do that to Castiel. This was the part of Dean, the real Dean Winchester, that was horrified by what he had done to the Stynes, what he had done to that kid, and was still trying to fight against the Mark.

But the real Dean Winchester was not strong enough.

That part remember that, yes, Castiel had beaten him twice before. The first time he had deserved it, but Cas had still saved Dean and followed him, blasting himself to pieces. The second time, after dropping the blade and breaking free, Cas had reached out and fixed what Naomi had broken. Dean's body and their bond had healed at the same time.

Now, though, Dean was leaving Castiel hurt on the ground, knowing that his powers weren't in top form. He was leaving him broken, which was something that Cas had never done to him in all of their years and trials.

Dean didn't notice the single tear that ran down his face as the real him wept for what he had done and what he could not stop.

AN: So, here's what my contribution to last week's episode. I just did this real quick, so expect some mistakes. I've wanted to write this all week and this was my only opportunity to do so, but I wanted it done and posted before the finale. This is kind of what I think was going on in Dean's head at the time. At least the Destiel flames are alive and well. Reverse Crypt Scene FTW, even if it was painful watching. Maybe I'll do something from Castiel's perspective, but don't expect it. After my current fic I'm working on, I want to do some Charlie and Castiel broness or maybe something involving the Impala. Let's survive tonight, everyone!

EDIT: I finally did a story somewhat from Castiel's perspective. It does mention what was going on during the reverse crypt scene a bit, but it focuses a bit more on the aftermath.