They had decided to close the gates of heaven.
All of them had decided. Sam was a fan of the idea. Dean wasn't so sure at the beginning but after meeting Naomi and her friends he changed his mind. Cas had been hesitant but when it came down to either now or never he had urged the brothers to do it.
Dean had suspected that there was something he wasn't telling them but he didn't push. Cas had promised that he would stay with them even though the gates would be closed so that was it.
He chose his human family over his angelic one. Dean could totally live with that.
So they did it. They had everything they needed and they just did it. No one interrupted them.
When Sam said the final words Cas turned to Dean.
"I'm sorry, I couldn't keep my promise", he said.
Dean's heart stopped and he took a step towards Castiel, who also stepped nearer. Cas grabbed Dean's wrist tight and held on. It hurt but Dean was not willing to shove him away. Not when there was a chance that he went back to heaven.
Cas closed his eyes when Sam finished talking and his grip tightened. Suddenly there was a light pouring from the back of Castiel's body.
It took Dean a moment to understand what happened but finally he understood that he saw Castiel's grace being ripped out of him.
Cas hand's clutched his wrists and Dean thought they would break but he did not really realize the pain. All he could focus on was Cas' grace leaving the body and he did not turn his eyes when they started to water. He wanted to see this. Needed to see this.
"Dean", Cas hissed. "Eyes." There was an urgency beneath the pain in Cas' voice that made Dean close his eyes.
The light still poured through his lids and he could tell when it made his way up to heaven because Cas fell against him and the light rose higher and higher.
Eventually everything went dark again. Dean could feel Castiel breath against him and after a few more moments, just to be sure, he opened his eyes.
Cas hang loosly in his arms and Dean carefully laid him on the ground and removed his hands from his wrists.
"Cas?" A light stirring was the only answer.
"Cas? What just happened? Are you still with me?" He felt that he started to panic when Cas still didn't move. He said he couldn't keep his promise but he was still clearly there. So what had Cas meant? Dean heard Sam approaching.
"Was that light Cas?" Dean shrugged. "So this means this is Jimmy then?"
Dean needed a moment to place that name but when it finally clicked he felt his blood run cold. He shook Cas, the body, Jimmy, again.
"Cas, buddy, I need you to open your eyes right now." He began to stir under his hands. Finally the blue eyes opened.
"Cas?", Dean asked a little scared.
"Hello, Dean," Cas said. Relief flooded his whole body. It was still Cas.
Cas tried to sit up but he seemed to have a problem with his body. "Cas what happened? What was that light?"
"It was my grace, Dean," Cas answered in a tone that made clear he stated something obvious.
"Your grace?", Sam asked. "Does that mean you're…", he trailed off.
"That I'm human? Yes." Dean felt the need to sit down so he just sort of fell back. Since he was already crouching besides Cas it was a fall of a few inches.
"You're human?" he asked, disbelief in his voice. "Why?" Cas met his gaze.
"When the gates of heaven are closed nothing angelic can stay on earth."
"So you just got your grace torn out because of us?" Sam shot a glance to Dean but he was busy checking on the angel. Ex-angel.
"No", Cas shook his head. "Usually the vessel would have been called back to heaven, too. I needed an anchor to stay put so that only the grace would have to return." Cas never broke this gaze with Dean. "So I held on to you. My grace left me and now I'm a mere human."
That was all way too much information for Dean to proceed so he just asked something else. "You said you couldn't keep your promise. But you're still here." Cas nodded.
"But I'm different."
"What?" Cas finally lowered his eyes. "You asked me to never change and I promised."
Dean immediately knew what promise Cas was talking about. He had said that to Cas after his little visit to the future back in the Apocalypse days.
"I couldn't keep this promise Dean. I'm sorry. I changed in every way." Cas still wasn't looking at him. Sam on the contrary burned a hole in Dean's head but he could explain later. Now he had to concentrate on Cas. Who was still looking at his hands.
Dean shook his dead. "No Cas. That's not true. You're still you. That's all that is important." He grabbed Cas shoulder. "You're still you and you're still here. That's all that matters to me."
Because the future-Cas version he saw was never going to happen to his Cas. He would make sure of that.
Cas sighed. "But I'm useless now. And I don't even know how to properly operate this body. It seems a lot more difficult now. And it is so heavy." He finally meet Dean's eyes again. Dean could see that he was still afraid and feared that he had somehow disappointed Dean.
Dean sighed again and pushed himself up, dragging Cas up in the motion. When the angel, ex-angel, he really would need time to get used to that, regained his balance, Dean pulled him into a tight hug.
"You're home now, Cas. Everything else will come."