Cas gave what was left of his grace to heal Sherlock. The inspector took a breath of life as Cas doubled over on the floor of the Tardis.
Dean rushed to Cas, kneeling next to him quickly. "Cas, hey, you okay?" he asked.
Cas had a far away look in his eyes, but he said softly, "Dean."
"Yeah, Cas, I'm right here," Dean said.
"No," Cas said, "I feel regret...about you and what I did to Sam."
"What are you talking about?" Dean asked. He started to get the feeling that Cas wasn't really seeing him.
"If there was time, if I was strong enough, I'd fix him now. I just wanted to make amends before I die," Cas said.
"Sam's fine," Dean said, "And Sherlock's gonna be okay. You're gonna be okay. Everything's fine."
Cas looked up at Dean, but his eyes weren't focused. The look gave Dean chills.
"Cas, are you hearing me?" Dean asked.
"Is it working?" Cas asked.
"Cas, c'mon. Snap out of it," Dean said.
Cas said quietly, "No."
For a brief moment, Dean thought Cas was actually responding to him, but the look on Cas' face told him different. He put a hand on Cas' shoulder and said, "Cas, please. We need you. Look at me."
"You?" Cas asked.
Dean stared at Cas' dazed expression, and the words Cas said started to sound familiar.
"I'm sorry, Dean," Cas said.
With the tone in Cas' voice, he knew exactly what Cas was talking about.
Dean looked at the Doctor and said, "He said this stuff to me a couple years ago after he became God. This was what he said before he died. Does that help at all?"
"After he became God?" River asked, confused, "He was God?"
The Doctor ran over to the scanner, staring at it intensely. "Regression? That is not good," he said.
Cas said, "I'll find some way to redeem myself to you."
"You already did, Cas," Dean said. He put a hand on Cas' face, kissed him softly, and said, "Come on. Come back. I need you. Please."
Cas blinked, eyes searching Dean's face. "Why am I on the ground?" he asked.
Dean helped him up and asked, "Do you know what you were just saying?"
Cas shook his head.
"You were saying the stuff you said before you walked into the lake with the leviathans," Dean said.
Cas squinted in confusion. "Why would I say that?" he asked.
The Doctor aimed his sonic screwdriver at Cas.
"Doctor, what are you doing?" Dean asked.
"I'm sorry, Dean," the Doctor said, "I need you to step away from Castiel."
"Cas? What? Why?"
"I didn't notice until recently, but I should've seen-It's very hard to detect, you see-I'm very sorry."
"Doctor, I don't-" Dean started, entwining his fingers with Cas'.
"Sam," the Doctor beckoned.
Hesitantly, Sam stepped forward and pulled Dean away from Cas.
"Sammy..." Dean growled.
Sam ignored him.
The sonic emitted its shrill tone as Cas looked over at Dean. "I love you," he said.
Cas melted into a puddle of milky white goop on the floor of the Tardis.
"Cas!" Dean shouted.
"Was never really here," the Doctor explained quickly. He pulled up the first scan he took of Cas.
"What do you mean he was never really here?" Dean shouted, "He was right there! He's been with us this whole time!"
"He was a flesh doppleganger. They are made to exactly copy a person to the point that they may believe they are who they copy. This must have been an advanced form of flesh in order to house even a little bit of angelic grace. It's really quite interesting."
"That's ridiculous. If he wasn't an angel, Gabriel would've noticed."
"Excuse me," Gabriel said, "But have you seen Cas lately? He became God, he became human, he stole another angel's grace. Of course he didn't look like himself."
Dean had to admit Gabriel had a point.
"Try to think about it. Why did he start saying things that didn't make sense?" the Doctor asked.
"I don't-" Dean said.
"Has he been gone from you guys for any extended period of time?" the Doctor asked.
"All the time," Dean said, "The guy doesn't usually stick in one place for too long."
"What about four years ago? Did anything happen around then to separate you?" the Doctor asked.
Dean tried not to think about what happened four years ago. Watching Sam fall into the cage wasn't something he liked to relive.
"It was the apocalypse. We were separated a lot," Dean said.
"It was the what?" River asked.
Dean ignored her. No need to explain the end of the world. "So, where's the real Cas, then?" he asked.
"The scan I first took of him says his skin was four years old. Actually..." the Doctor said, going through other scans, "His skin was exactly one day younger than Sam's."
Gabriel looked at Dean, and they both looked at Sam. Dean knew exactly where Cas was.
"Holy shit," Gabriel said.
Dean slammed his hand on the nearest railing angrily. He couldn't lose Cas again. He couldn't do it.
"We have to get him out," Dean said.
Sam said, "But this is the cage, Dean."
John gasped and asked, "The cage? Like Lucifer's cage? You can't really be considering opening it."
"We can't just leave him," Dean snapped. He sat on the steps leading up to the console, his back to the others.
Sam sat next to Dean and said, "Even if we decided to risk a second apocalypse to get Castiel back, how would we open the cage? We only have three of the horsemen's rings, and I don't think Death will just let us have his ring again."
"How do the rings work?" the Doctor asked, "Maybe we can find a substitute for the fourth."
"They seemed magnetic, but honestly, I have no idea. They're at the bunker if you want to look at them," Dean said.
"We can't open the cage, Dean," Sam pressed.
Dean stared at Sam in disbelief and said, "Sam, this is Cas we're talking about."
"He's been in there for over four years. That's nearly five hundred hell years that he's been in the cage with Lucifer and Michael. There might not be much left of him to save," Sam said softly.
Dean said quickly, "And he shouldn't be in there any longer. We have to get him out."
The Doctor put the coordinates for the Men of Letters bunker in the console.
Gabriel sat on Dean's other side and said, "Let's say we open the cage. Let's say we get it open, and Cas is still alive in there. The cage is strong enough to hold archangels for centuries. How are we going to get him out?"
"We'll figure it out," Dean said stubbornly.
Gabriel snapped, "No. We are not risking the planet again without a damn good plan, kid."
"Someone could go in with the vortex manipulator. They can grab Cas and come back," Dean said.
Gabriel gave Dean a sympathetic look and said, "Look, Dean. I get that you want Cas back, I do, but that probably won't work, and you'd be trapping one of us in Cas' place. If he went in for Sam, he knew he wasn't coming back. Could you really ask someone to do that for him?"
"We're not leaving him," Dean said angrily. He stood up and asked, "We need to get Cas back. Do any of you have a plan?"
The Doctor said, "Let's have a look at the horsemen's rings, and I'll get back to you on that."
Dean hung onto the railing as the Tardis transported them all to Kansas.
When they got out, Dean unlocked the door, and watched everyone file in. Honestly, he was shocked when Sherlock barely needed help to walk. Apparently, Cas' attempt at healing had done some serious good.
John's phone rang. He answered and said, "Hey, how are you? Are you okay?...Well, something came up, I'm sorry. We're...we're in Kansas. It's a long..."
Dean assumed it was Mary and decided not to listen in.
The Doctor quickly grabbed Dean's attention. "Where are the rings?" he asked.
Dean led him to the artifacts archive and pulled out the small warded box he'd put them in. He hadn't been too keen to leave the rings anywhere, but they were much safer in the bunker than they'd been in the trunk of his car. He handed the Doctor the rings and was almost shocked at how fast the Doctor whipped out his sonic screwdriver to examine the horsemen's rings.
"Are there any other ways to use the rings? There are several layers of magnetic pull, but they also seem to conduct their own sort of energy. I think my sonic should be able to replace the frequency of the last ring," the Doctor said, "If they connected in a different way, they may be able to do something other than open a hole into the cage."
Dean shrugged, but he knew where he could find out. He walked over to the paper archives where he was surprised to find Sam and Gabriel pouring through files.
River glanced around at the racks of paper stacks and asked, "Are you sure this is the most efficient way to store this much information?"
Dean ignored her and took a stack of files from Sam. "The Doctor says the rings may have other uses," he said, "You guys find anything about that?"
Gabriel took a breath and said, "I was there when God and Virgil made the rings. They definitely have other uses. They can open other doors to the cage, but it would be horribly, terribly dangerous on a level that I cannot impress upon you enough."
Dean asked, "Could we rearrange the rings to get Cas out of the cage?"
Gabriel grabbed Dean's forearm and fixed him with a deadly stare. "We could get Cas out, but it would leave the door wide open for Lucifer and Michael. Whoever went in after Cas would have to be faster than the two most powerful archangels in the universe. We'd be condemning the world," he said.
Dean looked at the rings in the Doctor's hands. He'd done stupider things for a whole lot less.
"Would an archangel be fast enough?" Dean asked.
Gabriel looked at Dean in shock.
Sam quickly said, "You can't ask him to do that."
"He just did, Sam," Gabriel said, "But I'm not faster than my brothers."
"We'd have the element of surprise. They wouldn't expect us to open the cage like that. It's an insane plan. That'd at least give you a head start. It's worth a shot," Dean said.
Gabriel said, "Even then, it is a huge risk, an insanely huge risk."
"Cas is worth it," Dean said.
Sam said, "You don't have to do this, Gabriel. I mean, Cas is family, but it's still a lot to ask."
Gabriel took a moment and looked at his hands. If he said no, not much would keep Dean from jumping into the pit and getting Cas out himself.
The archangel said, "Well, I guess it's just about time I made a self sacrifice play for my own brother, huh?"
Sam gave Gabriel a worried look, and it took everything Dean had not to hug the guy.
"Thank you," Dean said.
Gabriel stood up, clapped a hand on Dean's back, and said, "Anything for family, right?" He looked at Sam and asked, "Where's your room? After saving Dean this morning, I need to crash before I go to Hell tomorrow."
Sam led Gabriel down the hall as Sherlock asked Dean, "Is there anything we can do to help?"
Dean sighed, the thought of Cas being stuck in Hell tying his stomach in knots, and said, "Not really. Just be prepared for a potential apocalypse."
They'd save Cas. They had to.