"Yes," Dean choked out, anger and resentment seeped through him and into the solitary word. He balled his fingers into fists and stretched them back out again, slowly. He savored each movement as these would be the last decisions he would make for himself. Even the small movements he chose were comforting. He wiggled his toes ever so slightly in his boots as he turned his head to take a last look at his brother.
Dean's stomach clenched as his eyes met Sam's. Even while Sam was balled up in pain, the betrayal shone brightly through and it killed Dean to see it. "I'm sorry, Sammy." Tears began to make their way down Dean's face, dropping off his chin onto his black tee.
Sam struggled to sit up and lean on his elbow, pain radiating from him. Blood dripped out of his mouth, a grimace on his face. "Don't do this Dean. Please." His eyes were pleading and Dean felt like his heart would break in two.
Tearing his gaze away from his little brother, Dean turned back to face Zachariah. He took one hand and wiped it down his face to clear the tears away. "Didn't you hear me bitch? I said the damn word."
"Dean, Dean, Dean. So the time has finally come. You're finally ready" A smug look settled on the angel's face. "A big promotion will be in store for me after today. I finally landed the big fish. The big Kahuna!" He laughed and threw his hands up in the air. "The apocalypse is right on schedule and you –" he turned his hand to point at Dean – "are the star of the show."
"Just call Michael down, you bastard. Let's get this show on the road." Dean felt the anger starting to dissipate as acceptance settled in his bones. Acceptance that life as he knew it would be over. All the hunts for monsters a thing of the past, the times with his brother a distant memory. He knew Cas thought he was a failure for even considering this, but Dean knew better. Eventually, when the apocalypse was stopped by Dean's 'yes' – then they would understand. When he was able to stop Lucifer from destroying the world, they would understand his sacrifice. They would understand why he had to turn away from them. Why he felt compelled to make this decision. Why he betrayed them.
Dean could feel Sam's eyes on him, but that wouldn't stop him now. "Let's do this Zach." He took a slight pause, swallowing to lubricate his dry throat, before he looked Zachariah in the eyes. "Yes."
The ground started shaking and the picture frames started clattering violently against the walls. A high-pitched sound pierced Dean's ears and he clapped his hands over them and let out a scream. He suddenly felt a tingle all through his body, almost like a jolt of electricity. He wanted to curl up in a ball, but instead his head was involuntarily beginning to look towards the ceiling, his back arched, and his arms tensed, stretching towards the floor. His muscles were screaming at his brain, all completely taut and immovable. Every cell in his body was telling him to run, the fight or flight instinct kicking in. But no part of his body was responding to his commands anymore. A strong presence began to settle upon Dean. A force so completely overwhelming that Dean thought he might die simply from the weight of it.
This was it. This was the end for Dean.