A/N: This is sort of a speculation piece about whatever's going to happen this January. It basically goes along with the theory that Naomi and the other angels have "brainwashed" Cas and made him obedient again. Constructive criticism is much appreciated, as I've just started writing SPN fanfic and I'm still rocky on the characterization.
Dean knew it wasn't really Cas, knew it hadn't really been Cas since the nursing home, since before the other angels took him back up into Heaven and took out his heart and turned him into something painfully obedient. Even knowing it wasn't really Cas, though, didn't stop him from sitting up in the motel bed, from responding to those words he always responded to, because even if it wasn't really Cas, that burnt and broken shell of an angel standing across the room from him was the closest thing to Cas.
"Hey," he said, flipping his legs over to the side of the bed. He made no move to get up, trying to be calm and cautious for Castiel's sake. It was then that he flicked his eyes around the room and realized that they were alone. "Where's Sam?"
"I sent him away." The angel must've been really far gone, because the real Cas would have known how Dean would bristle at the ominous announcement, at the absence of his brother. Now, it alarmed Castiel, but he did well to hide it. "He's fine," said Cas. "For now."
Dean looked like he was going to get angry, but when he looked up to meet Castiel's eyes he just looked sad. Sad, and tired. "That's an angel blade," he pointed out, nodding to the weapon gripped in Cas's right hand.
"It was all I had," said Castiel. "It will work."
"To do what?" said Dean, and again, he should've sounded angry, or scared, but still it was just the sadness. His voice was steady, his gaze didn't waver, and neither did the blade as it glinted in the patch of moonlight from the motel window.
"Heaven's will," said Castiel, and he took a step forward. In one fluid motion from the bed to the floor, Dean was standing, facing the angel.
Now that they were at eye level, Dean could see the emptiness echoing out of Cas's blue eyes. Whatever had happened to him upstairs- and though Dean had tried like hell to find out, he still wasn't sure- it had left Cas more broken than he'd been before. Even crazy, even stuffed full of hungry Leviathans, he'd always been Cas, deep down, buried but alive. Now, Dean didn't know. He didn't know if the real Castiel was anywhere in there, or if he could ever come back.
Castiel raised the blade. There might have been regret in his face, for just a second, but it was gone before Dean could register it. "I have to do this."
"What do you want to do?" The angel blade remained motionless in Castiel's hand as the impact of Dean's words sunk in. He'd been asked the same question, in a cold room in Heaven by someone who didn't care nearly as much about him as Dean did. He had walked away from her and that question, but now? He couldn't walk away now, he had a job to do, and fulfilling that job, following orders, that was what was right. Wasn't it? "Cas, do you even remember anymore?"
And then he remembered, he remembered what he wanted, what he had done, what he was about to do. He remembered what he had to do, and he turned the angel blade around in his hands until it was pointed at his own chest. With every bit of resolve left in him, Cas drove the blade down.
It clattered to the floor before it ever touched him, knocked out of his grasp by Dean, and then there were hands pulling Cas's hands down and arms around his shoulders and Dean was pulling him in close and safe. "It's okay," he whispered against Cas's ear as he wrapped his arms tighter around the angel. "It's okay, Cas. It's okay."
His face was pressed against Dean's t-shirt, and Castiel was surprised when he felt moisture there and realized he was crying. Angels weren't supposed to cry, and doing something he wasn't supposed to felt right. He knew what he was supposed to do now. He was supposed to throw Dean off of him, reclaim the angel blade from the floor, and finish the job. Kill Dean- these were his orders.
And so, he wrapped his own arms around Dean and held the human that much tighter.