"No." Cas wasn't even sure where he found his voice because the air had left him. He didn't even bother explaining what he meant. He just said it again, his voice losing quality as he walked toward Dean. "No," he said. "No Dean. No. You have to go. Right now."

But, as angry as he was coming across, Dean had him matched. "No?" the hunter spat, "Are you freakin' kidding me right now? No? What the hell, Cas?" Dean's jaw was tight, his eyes livid as he spoke. And the energy between the two men was charged and intense. The last time Dean had looked at Cas like that, he'd beaten him until he was a bleeding mess underneath him. And a weird part of Cas remembered that moment, not fondly, but with a certain respect for what it was—a moment of honesty.

Cas glanced down to Dean's hands, balled into tight fists at his sides, and the angel swallowed, nodding in understanding.

"You figured it out," Cas said dully, not fully committing to his words as his eyes darted around the room. "How?"

"I found the book," Dean said, haltingly. "How long have you known these bastards were after you, anyway? Since you went to visit the kid?"

Cas hesitated, but Dean read the look on his face as confirmation.

"Damn it, Cas," he said softly. Then, a bit more brokenly: "I thought we were over this."

Cas squinted, tilting his head in confusion. "Over what?"

"Over you going off on your own. Over you setting yourself up as some kind of martyr," Dean looked furious, his fingers twitching at his sides like at any moment he could throw a punch or break something. In fact, Cas found himself waiting for just that. It wasn't beyond the hunter to find his emotional outlet at the edge of his fists.

But, what he wasn't prepared for was when Dean suddenly scooted back to the couch, deflating dejectedly as he sat down, propping his elbows on his knees and running his hands tiredly across his face.

Dean's expression softened a little as he hesitated. Cas zeroed in on Dean's face, seeing for the first time the lines and furrowed brows.

"You're worried," Cas said slowly.

Dean gave Cas an incredulous look. "Of course I'm worried you asshole," he spat. "When you find out demons are after you, the first thing you do is you tell me and Sam. Not go out looking for them on your own like you have some sort of crazy death wish!"

"Cas," Dean choked, continuing. "Don't you get it?" The hunter's jaw was clamped tight, his lips pursed as he looked up at a light on the ceiling. There was a long pause, and then: "I keep having to watch you die."

Cas looked in Dean's eyes and Cas couldn't only see it. He could feel the anxiety pouring off the hunter in waves. Cas vaguely marveled at how many times Dean's expressions conflicted with emotions Cas could feel radiating from him. It often left Cas confused and frustrated. But not now. Now he could not only feel it, but he could see it in the clearly on the hunter's face. The concern. For him.

"Please," Dean whispered. "Please stop doing this to me."

Cas swallowed, feeling a sense of guilt creeping into his chest. He didn't want to put Dean though this. But, as his mind drifted back to the smooth sketches inside the Seraphim book back at the bunker, he reminded himself he had to. He had no choice.

"I—" he started, feeling the sudden urge to apologize. But then he felt it. The microscopic vibrations in the air. Too subtle for humans, but the movement, to an angel was unmistakable. There wasn't any more time.

"I'm sorry Dean," Cas said, his voice changing back to a commanding tone. He needed to get Dean out of here. Now.

"You need to go," Cas said, reaching forward. "You don't understand," he continued. "This isn't something you can help with."

Then, as if it could ever be enough, Cas whispered, almost to himself. "Goodbye, Dean."

Dean's raised his hands to stop Cas, recognition finding him as Cas's hand neared. Out of the corner of his eye, Cas could see the lights in the room flickering as the floor started to shake, The photo of James and his aunt and uncle falling to the ground with the vibrations and cracking with impact.

"Don't you dare," Dean said acridly, pulling away from Cas's outstretched arm but he was cut off as Cas's fingertips touched the warmth of his forehead, sending him back safely to the bunker.

"I'm sorry Dean," Cas said to the empty space on the couch where Dean had been. But he didn't have time to dwell on it as the window to his left shattered in a loud firework of broken glass. Cas closed his eyes as the bulbs in the overhead light finally blew from the strain. Then, suddenly, room went dark. The quaking stopped and Cas held his breath. They were here.

Cas stared into the darkness, tightening his grip on his angel blade in the palm of his hand:

Here we go.