The ringing faded, as did the blinding white flash. A thump was heard as Billie's knees made it to the floor, whatever life that was once in the reaper now gone. Cas panted, unsure whether to feel relief the current risk was over, or dread towards the oncoming reaction. The hand holding the angel blade shook, spurring him into lowering it, as if keeping it in view was an insult to the situation.
The brothers Winchester, now released from Billie's hold, quickly jumped to their feet. Mary, in front of them, lowered her gun. Neither mother nor sons seemed to know what to think.
"Cas," Dean managed to speak. "What have you done?" The words were heavy and full of fear.
"What had to be done." Cas knew these words to be true. Letting any of the Winchesters die was not an option.
Sam and Dean shifted behind their mother, who appeared to be as shaken as the other two. The three of them had been ready to give up one of their lives for the Greater Good, this fourth option was not one any of them had thought of.
"You know this world, this sad, doomed little world, it needs you." Cas shook as he spoke, his actions and relief finally settling in. "It needs every last Winchester it can get, and I will not let you die. I won't let any of you die."
Cas could see Sam's eyes begin to water, and he could only hope it was because he was grateful for what Cas had done. But while he never wanted to hurt them, he knew that any reactions and feelings he and the others had would be worth it over them dying.
"I will not let you sacrifice yourselves," Cas continued, his voice wavering, heart breaking, eyes watering. "You mean too much to me – to everything."
Dean gulped. Sam shook. Mary looked as if her heart was heavy.
Anger filled Cas again as he thought of what they had all done. As if they really believed the world would be any better without any of them in it. As if he would be able to continue without any of them, especially Sam. "Yeah you made a deal. You made a stupid deal, and I broke it." Voice hard, Cas finished his speech. "You're welcome."
Unable to look Sam in the eyes any longer, Cas made his way to the car and got in the back seat. As he slid in, he remembered the angel blade, it's weight again becoming known in his hand. He banished it, yet no part of him felt lighter.
It took the rest of them a short time to join Cas in the car. Eventually, it was Sam who joined him in the backseat. Nobody spoke, and Dean never spared him a glance, his jaw clenched tight. Sam and Mary's apologetic looks were what kept him calm on the 6-hour drive home – Dean drove fast.
Cas had no regrets.