A/N: Again, I'm currently working on a few longer pieces - one of which is a Bones/SPN crossover. If you like my Bones/SPN crossovers (or any of my other fanfiction), stay tuned. More to come.

Booth's day couldn't get any worse.

It starts with the call from the Gravedigger, telling him that Bones is trapped somewhere, running out of air. That alone ruins his evening, because he spends the whole thing angry and worried and stressed.

He stays up all night at the lab, working alongside the squints to try and stop the Gravedigger, but eventually Booth has to go home to pick up a few things.

He only ducks into the apartment for a moment, but it's long enough.

As soon as the door clicks closed, Booth realizes something's wrong. There's something off about his apartment, the way the kitchen light is already on. Then, before he can grasp the situation, Booth finds himself pinned up against the door, a knife at his throat.

The intruder is a couple inches shorter than Booth, but by no means small, and he has strength enough to restrain a federal agent.

"You are Seeley Booth," the intruder says, and it's not a question.

Booth swallows, glancing down at the silver blade, then back up at the intruder. His gaze is intense, eyes squinted in concentration, jaw set.

"Slow down, buddy. I don't think you want to do this."

"I do not wish to kill you," he says. "I need your help."

"And you think threatening me will get you that?" Booth snaps, then bites his tongue. Snarking at the armed intruder probably isn't the best idea right now.

"I am simply disarming you." Booth feels a hand slip into his hip holster and remove the gun.

Then the man steps back, dropping his blade into a pocket of his tan trench coat. He removes the bullets from the gun with a practiced ease, then passes back the empty weapon.

Booth holds up his hands, stepping cautiously away from the door. "Okay, listen, I've had a really bad day, and if you're here to rob me…"

"I need your help," the man repeats. "You are an associate of Dr. Temperance Brennan?"

"Bones? What does this have to do with her?"

"You are aware that she's been trapped by a trickster."

"I don't know what you mean by trickster, but yeah, the Gravedigger. How do you know about that? That's classified. Who are you?"

"My name is Castiel," he says. He paces away from Booth, settling on the sofa in the living room. "I need your help."

"You keep saying that, but I need a little more information. What does this have to do with Bones?"

"My… friend, Dean, was taken with her."

Booth feels his entire body relax. Castiel, whoever he is, isn't here to rob or murder Booth. "You could have just said so. You didn't have to hold a knife to my neck."

Castiel glances upwards, frowns, and says, "My apologies. I did not intend to frighten you."

"What, and attempted murder isn't frightening?"

The corners of his mouth quirk upwards. "Not particularly, where I come from."

Booth stows away the information for later examination and sits down across from Castiel. "Okay, Castiel. This friend of yours… Dean. What was he doing with Bones?"

Castiel cocks his head at the nickname. "He and I are doing some… research here. He needed advice from an expert. We split up, and he went to speak with Dr. Brennan." Castiel frowns. "Then he went missing."

"How did you know he was trapped with Bones? Did you get a ransom call too?"

Castiel glances up, squinting his eyes at Booth. "No. He prayed to me."

"He-" Booth isn't sure what to make of that. "Excuse me?"

"He begged me to save him. But I cannot locate him, wherever he is; I can only hear his prayers. I hate it." He frowns, eyes going wide and distant and forlorn.

Booth reaches out a hand to awkwardly pat Castiel's knee. "Hey, it's okay, we'll find them. I've got a whole team working on this. If we'd known someone else was trapped with Bones we'd have reached out to their relations. I'm sorry."

"I will find them first," says Castiel, words certain and confident, "but I need your assistance."

Despite the fact that this man attacked Booth not a minute ago, Booth decides to trust him. If there's even a chance Castiel can save Bones, he has to try. "What can I do?"

"I need your phone."

Booth leans back, surprised by the request. "Excuse me?"

"I need to speak with Dean."

"Um, listen, Castiel… Wherever Bones and your friend are, there's no reception. I'm sure the Gravedigger thought of that."

Castiel shakes his head solemnly. "That is irrelevant. I can work around that."

"Um… how?"

"Your phone. Please." There's an edge of urgency to his voice, something Booth understands. He's just as desperate to find Bones.

So Booth passes over the phone. "Why do you need my phone? Don't you have one?"

"Yes, but unfortunately, Dean does not have his. And I did not have the phone number of Temperance Brennan. I needed your phone to make this call."

Finally, Booth begins to put the pieces together. Castiel knew Dean was trapped with Bones, and somehow he knew a way to contact Dean, but he needed Bones's number to do this. Hence the breaking-and-entering.

Castiel places his hand on Booth's phone, and for a moment a brief light shines through it. But no, Booth must be imagining that.

Booth tried calling Bones's number seventeen times after he heard from the Gravedigger, but each time there was no connection. Somehow, miraculously, this time the call goes through.

Castiel puts the phone on speaker and places it on the table between them. It rings once, twice, before it crackles to life.

"Hello?" asks Bones, and oh, Booth has never been so happy to hear her voice.

"Bones," he says, relief seeping through the word. "You're alive."

"Booth? Is that you?"

"Yeah, yeah, it's me. Are you-"

"Where is Dean? Is Dean all right?" Castiel interrupts.

"Who's that?" Bones asks.

"Is Dean all right?" Castiel repeats, leaning forward anxiously.

"Yes, he's fine, he's-"

Booth hears a muffled sound on the other line, and then a gruff, unfamiliar voice.

"Cas? Cas, are you there?"

"Dean," Castiel says, and Booth hears the same relief in his tone.

"What's going on, Cas? Is it the trickster? Why am I trapped in a car with some forensic anthropologist?"

"You're in a car?" Booth asks. Any information is important.

"Yeah, uh, somewhere underground. Who's that?"

"My name is Agent Booth. I'm with the FBI, I work with Dr. Brennan."

Dean swears and says, "Come on, Cas, you brought the feds in on this? You know that won't end well."

"He's the closest relation of Dr. Brennan's, and the one who received the ransom call. He was my only option in finding a way to contact you."

"I prayed to you, Cas." There it is again, the idea of prayer. Whatever the codeword means to them, it seems important. Dean's emphasis on the word doesn't go unnoticed.

"And I heard you. But, I suppose because you are underground, my 'angel radar' doesn't pick up on your location. It's been rather aggravating. This was my only way of finding you."

Dean says something muffled on the other side, and then, louder, "Listen, I'm putting you on speakerphone. The doctor wants to talk."

After a loud click, Bones says, "Booth, it was the Gravedigger. He knocked me out. Dean was there, he tried to protect me, I think. It's all a little fuzzy."

"Yeah, I know. Don't worry, Bones, we're going to get you out of there. I promise. The whole team's working on it."

"I will rescue you," Castiel affirms. "Dean, tell me of your position."

Dean grunts and says, "This would be a helluva lot easier without the sigils on my ribs, you know. You could just pop in and zap us out of here."

Booth doesn't understand what Dean means, but it must mean something to Castiel, who smiles softly.

"I have to ask," Bones says, "how did you manage to call me? There is no reception down here."

"I altered the abilities and wavelengths of Agent Booth's mobile phone," Castiel says, as if that explains everything.

Dean laughs. "Friggin' angels."

"That's impossible," says Booth. "You barely touched my phone."

Castiel gives him a look that says, don't ask questions. So he shuts up. Besides, there are more important things to focus on right now.

"Dean, are you sure you're all right?" Castiel asks, tone quiet, worried.

"Yeah, yeah, sheesh, I'm fine. My head hurts; I think the trickster pistol-whipped me or something. Hey, any progress on catching the son-of-a-bitch?"

"Are you talking about the Gravedigger?" Booth asks, glancing over at Castiel.

Castiel nods. "I believe so. We were both separately tracking down the same murderer – someone who enjoys toying with others' lives for the sheer pleasure of it."

"Booth," Bones cuts in, "I think I know of a way to get out, but I'm not sure it would work. I'd have to discuss it with Dr. Hodgins. Can you talk to him?"

"I can call him and ask him to come here. It'll take him some time to drive over. And… I'd have to hang up, so we can use the phone." Booth looks uncertainly at Castiel. "We could call her back, right? The line would still work?"

"Yes."

"Then we'll do that. We'll call back in a few minutes, understood?"

Dean mutters something unintelligible. Then, louder, he addresses Castiel: "You call right back, you hear me? If you fuck this up, Cas, I'm going to kick your ass."

Booth sucks in a breath. "If we mess this up, Dean, you'll be dead."

Dean snorts. "That's never stopped me before."

Booth isn't sure what to make of that, so he presses end call.

It only takes a few minutes to call Hodgins and explain the situation. Hodgins says he'll be at the apartment as soon as possible, so they say their goodbyes. Booth is already redialing Bones's number before he's even ended the call.

This time, Bones picks up on the very first ring.

"Hi again," Booth says.

"Dean? You're still safe?" Castiel asks. He seems very worried about Dean. Booth is terrified for Bones, but at least he's not babying her. He knows she can take care of herself.

Dean seems to be equally frustrated by Castiel's concern. "Dude, you were gone for what, three minutes? It's not like I could hurt myself seriously in that time. I'm fine. Quit your worrying."

Castiel shakes his head, frown building. "You're in danger, Dean, a danger from which I can't protect you. I don't like it."

Dean laughs. "When am I not in danger?"

"This is different. Demons, angels, I can fight. Not this."

Booth blinks slowly. That's the third time angels have come up in the conversation. The things these two say don't make any sense. Maybe they're delusional religious fanatics.

Dean makes jokes about coming back from the dead, Castiel carries a sword, and Dean's implied several times now that danger is a daily occurrence for them. What kind of life do these two men live?

Plus, there's the fact that they were tracking down the Gravedigger. And clearly neither of them are police or CIA. Who are they?

Bones seems to be thinking the same thing. "You two are very close, aren't you? Dean, you told me you were certain Castiel would save you. How are you so certain of your faith in this man?"

"He's saved me before," says Dean. "He's not going to let me die."

"Damn straight," Castiel grumbles.

"That's how you feel about your partner, right?" Dean asks. "Agent Booth? You'd do anything for Dr. Brennan, wouldn't you?"

"Absolutely."

"That's me and Cas."

Castiel looks down at his hands. "Our relationship goes beyond professional, Dean."

"So does ours," Bones says. "Booth is my best friend."

Booth is floored by the praise. He might have thought of Bones this way in his mind, but hearing it from her mouth is a different thing. He stutters, "Likewise," and leaves it at that.

Dean snorts loudly. "Yeah, but you aren't screwing him too, are you?"

Booth blushes at the implication. Clearly, Dean and Castiel's friendship goes beyond what he'd imagined. No wonder Castiel is so concerned for Dean's safety.

Bones considers this for a moment, then addresses Booth: "Hodgins is on his way?"

"Yeah. We'll get you out of there soon, I promise." He doesn't add how worried he is. He doesn't add how he wishes their relationship could be more like Dean and Castiel's.

Castiel leans forward and says, in a low, intense voice, "Dean, when I find the one responsible for this, I will smite him with the power of a million suns. He will not go unpunished."

Booth's not sure what to make of that threat. Should he take it seriously? Should he arrest Castiel?

The fact is, these two men have both said some incriminating things. Plus, Castiel did assault a federal officer. But Booth can't arrest them. Dean's just as trapped as Bones, and Castiel's just as desperate. Desperate times call for desperate measures. Booth won't blame Castiel for his actions.

For a long moment, they sit in silence. Booth doesn't know what to say – anything personal is overheard by these two strangers, but if these are his last moments with Bones… No, God, they can't be. He'll save her. He has to.

"Dude, cut it out," Dean says, breaking the tension. "I can practically hear you worrying over the phone line."

Booth smiles slightly and glances over at Castiel, who is, as predicted, terrified.

Castiel doesn't look remotely comforted by Dean's humor. "This isn't funny, Dean. You could die."

"Yeah, and then you'll just bring me back. I don't see a problem here." Okay, Booth definitely has to think that one over. Maybe these guys are psychotic.

Castiel just shakes his head. "You have too much faith in me, Dean."

"That's not what you said the first time we met."

Booth wonders, briefly, how these two characters met, but doesn't dwell on it. Besides, what Castiel says next is much more distracting.

"You don't understand how frustrating this is, Dean. I pulled you out of Hell, I fought by your side in Purgatory, but I can't save you from one damn underground car."

"Cas, you are saving me. You just have to be patient, until Dr. B's scientist friend gets here."

"He's right, Castiel," Booth cuts in, although he's not sure he should intrude on their conversation. He understands how close they are. "Thanks to you, we're able to communicate with them. I don't know what I would have done without your assistance."

Castiel fixes that intense gaze on Booth. "You would have saved her. You would have found a way. I have not lived among you for long, but I know enough about human nature. We save the people we love."

Booth's mouth goes dry at the last word, but of course it's true. Castiel doesn't mean romantic love anyway. Booth has always known Bones is more than just a coworker. He cares about her, and he won't just let her die. Not if he can stop it.

At that moment, Hodgins knocks furiously on the door.

Booth quickly makes introductions, and while Hodgins looks a little nervous under Castiel's steely glare, he doesn't lose his cool. He plunges immediately into the conversation with Bones.

"I was thinking," Bones says, "if we could form some kind of explosion, it could give us the power to escape. I could blow up the air bag. But I wasn't sure what the ramifications would be, so I needed to speak with you."

Hodgins frowns, mind whirring with mental calculations. "That could work, Dr. Brennan. But it's too risky. You know it's too risky."

Bones sighs. Clearly, the two of them see something Booth doesn't. It seems like a great idea to him. "I know. I thought of that too."

"What? Thought of what?" Dean asks gruffly.

"That kind of explosion can't be contained in a small space," Hodgins explains. "If you're less than four feet from the surface, great. You get out. But if you're further down than that, your brains will turn to jelly."

"Oh. Great." Even through the phone, Booth can hear Dean's unease.

"We have to do it," says Bones. "It's our best shot."

"No," Booth says firmly. "We have enough time. We'll find another way, a safer way. You're not going to risk your life like that."

"Why not?" asks Dean. "Come on, Cas, we make these gambles all the time, and we always come out on top. I'll be fine."

"We don't always come out on top," Castiel reminds him. "May I remind you of the number of times you've died? And I've had to drag your ass out of Hell or Heaven or wherever it is you've landed yourself?"

Dean laughs. "Okay, so you can just do it again. You know me, I never stay dead very long. Listen, Dr. Brennan and I will be fine."

These two are something else. Booth would love to hand them over to Sweets, but he has a feeling they won't be sticking around long, once Dean is safe.

"May I give my opinion?" asks Hodgins. Booth glares at him, but lets him continue. "Booth, I know you're worried about Dr. Brennan. I am too, believe me. But this really is our best shot at saving them."

He knows they're right, but he hates this. He hates risking her life like this. "Fine, say the explosion does work. They still have to dig their way up from four feet underground."

Dean just laughs. "It's okay, Agent, I've done it before."

"You've- what?"

"You've been buried alive before? Why didn't you tell us? That could have been useful knowledge when-" Bones starts.

"Yeah, no thanks to Castiel over here. You'd think an Angel of the Lord would remember that when he pulls a guy out of Hell, he should check and make sure said guy isn't six feet under. But no, he was too busy being a wavelength of celestial intent, nope, no time to bust me out of my coffin." Dean's voice is dripping with sarcasm, clearly reopening an old argument. Although who argues about these things in their free time, Booth doesn't know.

Bones, ever the rationalist, ignores the bizarre response and presses on. "You think you can get us out?"

"Yeah. I promise. I'm not letting you die, Dr. Brennan."

There's a note of honesty in Dean's voice, and even though Booth doesn't trust the man's sanity, he finds himself trusting Dean with Bones's life.

Still... "Bones, I can't let you do it."

"It's my choice to make, Booth. You can't stop me."

"Maybe I can't, but just… please, Bones. Don't do this."

When Booth looks up from the phone, Castiel is staring at him again.

"What?" he snaps. "You wanna tell me to stuff it too?"

Castiel cocks his head to the side, eyes squinting. "You're in love with this woman."

"I- what?" No, Castiel can't know that, no one knows that.

"You are," Castiel reaffirms.

The line crackles with energy, and Bones says, "What was that, Castiel? The line went staticky on our side for a second." Booth breathes a sigh of relief. She didn't hear Castiel's words.

Unfortunately, Hodgins did, and he's now staring at Booth like he's grown an extra head.

"You're crazy," Booth says, but he's never been much of a liar.

Castiel just nods gravely. "So I've been told. I promise you, Agent Booth, Dr. Brennan will not be harmed. I will personally see to it."

For a moment, no one says anything, not even Hodgins. Then, finally, Dean speaks up.

"Okay, are we doing this? 'Cause we'd better get a move on. Sam's probably getting pretty impatient, Cas."

"I informed him of your situation. He's on his way to D.C. as we speak."

Hodgins looks at Booth and mouths, Sam? But Booth just shrugs his shoulders.

Castiel, without even glancing over at them, picks up on their confusion. "Sam is Dean's brother," he explains. "He's panicking."

Dean laughs. "You'd think after all the rodeos we've been through, you two would quit worrying about me."

"Somebody has to look after you, since you won't." Castiel's tone is annoyed, but his eyes are soft.

"Whatever. Dr. Brennan, can we really do this?"

"Yes. I just have to activate the airbag. It will only take a matter of seconds."

"Cas. When we're out, you'll be here?"

"As soon as you surface, you tell me where you are, and I'll be by your side."

"You promise?"

"I promise."

Booth catches on slowly to what they're saying. "Wait, hang on, you'll be there immediately? How are you going to do that?"

Castiel looks at Booth, squints his eyes, and says, "I'll fly, of course."

"Excuse me?"

"Listen, Agent," Dean cuts in, understanding what's going on, "Castiel has some… abilities. For the moment, if you want Dr. Brennan to be safe, you need to suspend disbelief and trust him. He'll find us, and he'll bring Bones to you. Just don't ask questions."

They're implying that Castiel can teleport.

Oh. Maybe they work for the government. Then it all makes sense, of course. The way they talk about danger like it's a daily occurrence, their mysterious codewords, Castiel's impossible ability to create universal phones out of regular ones. If it's true, their security clearance is far, far above Booth's. He remembers Dean's reluctance to bring a federal agent into this. It must be because Booth isn't supposed to know about these things.

It doesn't matter, though, none of it matters. Not if he can rescue Bones.

Hodgins, king of the conspiracy theories, must have figured this out some time ago. After this is all over, Booth will ask his opinion on it. But right now, he needs to focus, and he needs to trust these men.

So Booth agrees, albeit skeptically. Then, he turns to Castiel. "When you go to them, you're taking me with you."

Castiel frowns. "What?"

"You're taking me. That's final," he insists. "I'm not going to let Bones be alone. If you go to Dean, I go to her."

Castiel considers this for a long moment. "Fine. You can come with me."

Booth breathes a sigh of relief. Somehow, in a few moments, he'll be seeing Bones.

"Dean says most humans do not like flying. They find it unsettling," Castiel warns.

"That's okay, I can live with it," Booth says. Only afterwards does he realize Castiel referred to humans as if he wasn't one of them. What?

Maybe he's not a spy, maybe he's an alien, with extraterrestrial powers... No, that's crazy. If Booth is starting to believe in aliens, this has gone too far. Even the super-spy idea is a little far-fetched. Booth needs to stop theorizing and focus on the facts.

Fact. Bones is in danger. He shakes his head, clearing it, and turns back to the phone.

"We're hanging up now," says Dean, "to do the thing with the airbag. Cas, if this goes south, I'm trusting you to get your ass up to Heaven and resurrect me. Or something. I'm not going to be killed off by a fucking Trickster, got it?"

"I have 'got it.'"

"And, if this does end badly, I... Aw, hell, you know."

"Yes, Dean, I love you too," Castiel grumbles. Clearly this isn't the first time they've gone through this possible-last-words-I-love-you routine.

It's sweet, Booth decides. They're sweet, in an unconventional way. Even just hearing them talk over the phone, Booth knows that. He sees how worried Castiel is.

He wishes he could say the same to Bones. Instead, he just tells her, "Be safe. Bones…"

"I'll see you soon, Booth."

The line clicks dead.

For a long, pregnant minute, they sit in silence. Booth isn't sure how Dean's supposed to contact Castiel, but when he opens his mouth to ask, Castiel shushes him impatiently.

Castiel sits, muscles tense, eyes squinting at some point in the middle distance. Booth gets up and paces.

This could go either way. Bones and Dean could be dead by now, or they could be crawling their way towards the sun.

Suddenly, Castiel jerks to his feet. Booth spins, and he knows at once from Castiel's expression what's happened.

"Come," Castiel says, laying a hand on Booth's shoulder.

He blinks, and when he opens his eyes again he nearly passes out from the disorienting shock.

They're in a different place now, gone from the apartment to a gravel and silt pit, and the sun is hot and bright and for a moment, Booth sways in place.

Then he focuses on Bones calling his name.

He runs to her, not bothering to see if Castiel follows. She's halfway out of the dirt, gravel in her hair and in her clothes, voice raw from shouting his name.

"Bones!" He grabs an arm and a shoulder and pulls, lifting her out of the dirt and into his arms. "Oh, God, you're all right. Thank God you're all right." He presses a kiss to the top of her head.

"Close, but not quite," says a voice from beside him. "You should thank Castiel."

Booth turns his head, and beside Bones is another stranger, fresh out of the dirt as well. This must be Dean. Castiel knees in front of the man, hands wrapped around hands, checking for injuries.

Booth ignores the comment, although he knows Dean is right, and instead turns back to Bones.

"You're okay? You're really okay?"

"I'm fine, Booth." Bones pushes out of his arms and stands up, still a little wobbly. "The sun is a little bright, and the oxygen in my bloodstream is a little thin, but I'll be fine."

"Let's get to Sammy," Dean says from behind them. A moment later, he hears a sound like wings.

Booth twists to thank Castiel, but when he looks to the spot where Castiel and Dean stood just a moment ago, they're gone.