Cas pulled the blanket tighter around himself and shivered harder in the chilled air of the cave. He stared at the line of salt encircling him, wondering for the hundredth time if he should cross it, if the Winchesters had been gone too long, if they needed his help. But as much as he hated to admit it, he could tell by the tremors running throughout his body that he wouldn't prove much use to them. He wasn't even sure if he could stand.

There was a scuffle of movement at the cave's entrance, and Cas raised his head warily. Then, he heard Dean's voice, and he relaxed.

A few seconds later, Sam came into view, followed closely by Dean, who was holding an armful of wood. Cas frowned. Sam seemed to be holding himself stiffly - was there something wrong with his side?

And then Cas saw the blood. He was on his feet in an instant, and then, just as quickly, was back on the rocky floor of the cave, cheek pressed into the dirt.

"Whoa, Cas, stay there," Dean's voice cautioned him, and Cas pushed himself slowly upright.

"Sam-" Cas began, but the younger Winchester was shaking his head.

"I'll be fine," Sam said. "The scratches aren't that deep."

"I can heal you," Cas insisted, and Dean nodded, moving forward with the wood.

"Yeah. After you warm up some. You're a friggin ice cube." He shot a look at Cas, the one that meant "you're annoying me, but only because I'm worried about you." Cas saw this look a lot.

"What happened?" Cas asked weakly, temporarily (but only temporarily) giving up on the idea of healing Sam. Instead, he looked towards the younger Winchester with worry.

"He was being a dipshit and a stegosaurus attacked him," Dean said with a small smile before Sam could volunteer any information. "It was self-defense."

"Oh, that's great, man," Sam said with a groan. "Stick up for the dinosaur."

"Big guy needs a friend, if scary Sasquatch people are yelling at him and waving their arms around."

Sam huffed in exasperation, and Cas felt a little better as the brothers squabbled amicably. If they were fighting about stegosauruses, Sam really must be alright.

Sam put a hand on the wall behind him and started to lower himself to the ground. He winced and exhaled sharply when the twisting movement put pressure on his wounds, but Dean was immediately there, helping support his weight as he breathed through the awkward position and sat back against the cave wall.

"Can I step outside the circle yet?" Cas asked. If he really wanted to move there wasn't much they could do to stop him, but he figured he might as well be polite.

Dean took his eyes off Sam for a second to eye Cas up and down. "Ummm, no," he finally said.

"What?"

"You're dead on your feet, Cas. Just sit there and let me get the fire started."

Cas sat down in a huff. He'd just wanted to go help Sam. Not try to heal him, just help him put pressure on the wounds without straining the muscles and bones in his chest, which were probably injured as well. But if Dean really thought that Sam would be fine, Cas supposed there was nothing he could do.

Cas watched as Dean busied himself making a fire just a few feet outside of the salt circle. Cas figured it was at least somewhat lucky that it had been him who had been dropped in the river and not Dean, because within a few minutes Dean had a fire started courtesy of the lighter from his backpack, and Cas didn't know where they'd be if they'd had to start a fire from scratch. As far as he knew, Dean didn't know how.

"Okay, come sit over here," Dean finally said, gesturing slightly at the small but crackling fire. "Get yourself warm."

Cas finally left the circle and settled himself down next to the fire, while Dean laid Cas's still-soaked clothes out next to him to dry. Dean was completely right, within only a few minutes of sitting next to the fire, Cas felt far better. His fingers tingled with pins and needles as they came back to life, but he hadn't realized how tightly he'd been clenching them and it felt good to let them relax. He had little crescents bitten into his palm from his nails.

"I'm ready to heal Sam now," Cas finally said. Both brothers immediately looked up at him suspiciously.

"You sure?" Sam asked. His face was pale, and there was some blood on his forehead where he must have accidentally smeared it.

"Yes."

Cas pushed himself to his feet, glad that he had no trouble getting his legs to take his weight. He walked to Sam and knelt in front of him, then gently touched two fingers to Sam's forehead.

Sam watched the angel carefully as Cas frowned, fingers still touching his forehead. Slowly, he felt a warmth diffuse into his being, localizing in his side. The pain in his ribs eased, and Sam could almost feel the wounds closing. He waited for the flesh to knit completely, but Cas paused, opening his eyes, looking white and shaken.

"What is it?" Dean asked sharply, beginning the hover, and Sam could see the indecision as his brother tried to discern which one of them he should be worrying over.

"Cas, you okay?" Sam asked, shooting Dean a "don't worry about me, I'm still fine" glance. Dean narrowed his eyes slightly, but must have decided that Sam was telling the truth, because he switched his gaze over to Cas.

"What's up?" he asked the angel, who'd gone a few shades paler again.

"My grace...it's drained more than I thought," Cas said, a little shakily. "I-I didn't realize how challenging it would be to send us back so far. Even something as small as healing Sam is...difficult."

"It's alright," Sam said hurriedly, before the angel could do something stupid like try to finish the job. "Really. You got most of it, I feel a little sore is all."

"I don't want to leave you vulnerable," Cas insisted, but his voice was trembling slightly, and Sam knew he'd already won the battle.

"I've fought through way worse with a lot more than a few scabs," Sam said with a chuckle, pulling himself to his feet with barely a pause. His side did feel much better. It was sore, yes, and he could still feel a dull ache in his ribs, but the angel really had helped.

"You should save your strength," Sam continued. "Recharge a little."

"Yeah," Dean finally said, reluctant though it might be. "We might need a little angel juice later."

"Are you sure?" Cas asked, getting to his feet and standing, a little unsteady.

"Get some rest," Dean told him, and Cas shook his head.

"I don't-"

"Sleep, yeah, we know. Just...humor us, okay?"

Cas nodded slightly and Dean shooed him back over to the fire, where the angel sat back down and wrapped a blanket around himself. Sam went to join him, but Dean pulled him back.

"Sam, you sure you're good? We're back in the Jurassic, which is fucking awesome, but it also means we can't exactly make it to an ER if things go sideways."

Sam nodded. "Seriously, Cas helped a lot. See for yourself."

Sam turned to give Dean a look at his side, and heard his brother make a small, satisfied sound in the back of his throat.

"You'll live," he proclaimed. "Now get some sleep."

"But we should keep watch-"

"I know we should keep watch," Dean said quickly. "And seeing as I'm the only one who's managed to not damage myself yet, I'll take first shift."

"But-"

Sam knew Dean well enough to know that you could not let him take first shift. He would stay awake through the whole night. Which was obviously unfair, but also left him bitchy and groggy the next day, which Sam knew was not something they could afford, not here.

Dean apparently knew what Sam was thinking. "I promise I'll wake you," he said. "Or, I'll probably get Cas, since he doesn't sleep anyways. But I won't stay up the whole night."

Sam nodded. He wasn't completely satisfied, but he supposed that was the best he was going to get. And Dean was right, he did need sleep. The "fight" with the stegosaurus had left him drained, even after being healed by Cas, and he knew he would feel better after getting at least a couple hours sleep.

Not that this was going to be comfortable. Sam, Dean, and Cas had each stuffed a thin camping pad into their backpacks, but there'd been no room for sleeping bags or anything like that. Luckily, the fire was keeping the cave bearably warm, but once the sun had set the air outside had grown dangerously cold. Sam didn't think there was anything he could do aside from pile on layers and lie as close to the fire as he could. He unrolled his thin sleeping mat and sighed.

"Goodnight Sammy," Dean said from where he was perched at the front of the cave.

"Goodnight."

Sam woke up to a cold hand shaking him. He automatically reached for the gun he had under his pillow, then realized not only could he not feel the gun he didn't even have a pillow. Then, slowly, he blinked his eyes open and looked around. Right, the cave. Dinosaurs. It was clearly the middle of the night, or possibly even the early morning, but he didn't have a good sense of how much time had gone by.

It was Cas who had woken him.

"It's time for you to keep watch," the angel said.

"Dean woke you up?" Sam said, somewhat surprised.

"No. But I took over when enough time had passed."

"Okay," Sam said, pushing himself into a sitting position, trying to shake the sleep from his mind. He looked over at Dean, trying to ascertain that he was actually asleep. His breathing was deep and even, and there was no way that Dean could fake that.

Sam breathed a small sigh of relief, glad that his brother had done the sensible thing for once. Knowing Dean, he'd still probably stayed at his post longer than his share, but at least he'd gotten some sleep. Sam turned his back to the fire and his face toward the entrance of the cave, waiting for morning to come.

There was something tickling Dean's nose. The sensation worked its way into his dream, something bizarre with talking broccoli and AC/DC, and he wrinkled his face. Then, his brain caught up with his body and Dean shot upright, lashing out at whatever was in front of him, wrenching something small away.

"Morning to you too," Sam said laughing, and Dean blinked sleep away to find himself tightly clutching a granola bar. Sam was a few feet away, going through the pack that held their food.

"Why can't you wake me up like a normal person?" Dean muttered, ripping open the bland and tasteless bar that Sam had apparently bought.

"Well, you tend to stick guns in my face," Sam pointed out. "Besides, my way is a little funnier."

Dean huffed silently and took a bland and tasteless bite of the granola. He looked towards the mouth of the cave, where Cas was perched, looking out at the landscape.

"He looks better," Dean said to Sam, mostly to take his mind off the bland and tasteless breakfast. It hadn't even been a day, and he already missed coffee.

"'He' can hear you," Cas remarked, turning to face them. "And yes, I feel at least somewhat better. I don't think I'll be able to regain my full strength until we return to our own time, but I can feel my grace regenerating."

"That's great," Sam said. "We were worried."

"Okay, so which way did Gabriel say we should go?" Dean asked. Cas peered back out at the desert, probably searching for landmarks.

"Towards a lake, if you can see that," Sam told Cas. "Dean, if you aren't going to eat the granola bar, give it back."

Dean started guiltily, realizing that he'd been slowly mushing the bar around, avoiding actually putting it in his mouth. "Hippie food, Sam," he muttered.

Sam frowned, pursing his lips into his patented "holier-than-thou" face.

"And don't tell me that it's 'healthy,'" Dean said emphatically. "It's disgusting. If you're tryin' to get me to eat that crap, find something that tastes a hell of a lot better." He tossed Sam the remaining granola bar and stood up, rolling his sleeping pad and clipping it back onto the backpack he'd brought.

A few minutes later, their small, makeshift campsite was completely packed up, Sam had pressed a bag of beef jerky into Dean's hand, and they were ready to move. Dean looked over the other two carefully, trying to make sure they were, in fact, alright to start moving. Sam looked okay, a little stiff and pale but nothing worse than they would experience after a run-of-the-mill hunt. Cas looked a bit worse off than Sam did (Dean supposed the spell was still tugging at his grace) but he also looked grimly determined, and when he started walking around his gait was steady.

All three of them hoisted their packs onto their backs, and before long they were headed towards what may have been a lake spotted by Cas in the distance, but may also have been nothing more than a smooth patch of rock or possibly a weird shadow.

"How long do you think it'll take us to get there?" Dean asked. As much as he liked the fact that they were walking through Utah in the actual Jurassic Era, he could not deny the fact that he simply didn't like hiking very much. There weren't many visible dinosaurs around, either because it was too early or because the three men were too loud, and he was already hot and kind of hungry and ready to sit down and break for lunch.

"I mean, probably a while," Sam said. "We've only been walking for about ten minutes."

Dean didn't respond. The gravel and sand crunching beneath his boots sounded oddly loud. Maybe it was because everything was quieter here. There was no...general hum of life the way there was in 2018. Also, no birds.

"I spy with my little eye-"

"No!" both Cas and Sam said in unison. A certain expression must have crossed Dean's face, because Sam at least had the decency to look somewhat repentant.

"At least...not yet. We're not bored enough. We need to save it."

Sometimes during long car rides where he and Sam knew they might get bored or start to fight, they saved the best games, the most reliably entertaining ones like "fuck, marry, kill", for when they were already a few hours in. It helped to have something to look forward to, and then they hadn't tired out their best games before they really needed them. Dean supposed he understood the logic of this, but he hated hiking enough that it didn't seem fair.

It seemed to take forever for them to finally reach the lake that Cas had spotted, but at least by the time they got close they could tell that it was, in fact, a lake. Not only that, but there seemed to be a non-zero amount of dinosaurs crowded around it, which was all that Dean had really wanted out of this day from the start.

Dean poked Sam in the arm, nodding excitedly to the herd (herd, there was a herd of dinosaurs) around the lake. "Look, Sam, diplodocus!"

"How do you even know that?" Sam asked, shading his eyes and looking toward the lake. "The long-necked ones?"

"Well, some of them," Dean answered. "The bigger ones kinda look like they might be brachiosauruses."

Sam's eyebrow twitched in confusion, and Dean rolled his eyes. "You don't get a corner market on fun facts, nerd. Not my fault you skipped the dinosaur phase."

"Thank you, Dean," Cas said, a little tetchily. "But we only have about thirty-six hours to find Gabriel, get the plant, and make it to the 'extraction point.' I suggest we hurry."

"Extraction point?" Dean asked, grinning. "Nice."

"You made me watch 'Mission Impossible,'" Cas grumbled, starting off down the hill. "The title was misleading, the mission was entirely possible."

Sam opened his mouth to say something, paused, then shut his mouth and followed Cas. Dean swallowed laughter and joined the other two, walking towards the dinosaurs.

Sam followed closely behind Cas, turning around every so often to make sure Dean was still with them. His brother was absolutely ecstatic, grinning like a little kid and trying to turn in every direction at once.

"That one's smiling," Dean said excitedly, pulling out his phone and snapping what had to be the thousandth picture.

"I think it's eating," Sam said, eying the dinosaur dubiously. "Or maybe grimacing. Do dinosaurs have facial expressions? Maybe it's trying to decide if it wants to eat us."

"It eats plants, Sammy," Dean said absentmindedly, taking yet another picture. "So unless you've stuffed enough salads down your throat to count as a vegetable…."

"It could step on us," Sam muttered, rubbing surreptitiously at his still-aching side. "Cas, do you know where Gabriel is?"

Cas shook his head. "I'll have to ask them."

"YOU CAN TALK TO DINOSAURS?" Dean's head whipped around so fast that Sam was momentarily worried it would come off.

"Well, I can determine if one is an angel's vessel," Cas answered.

Dean paused mid-picture. "Hold on. Vessel?"

Cas sighed. "Yes. At this time, the angels were busy in Heaven, trying to make God's plan come to fruition. All except for Gabriel. He always was a bit of a free spirit."

"Are you...are you telling me that Gabe is in a dino? Gabriel is a dino? We're lookin' for dino Gabe?!" Dean's mouth had fallen open.

Sam didn't know what he had expected, exactly, but he knew this wasn't it.

Cas shrugged slightly, looking thoroughly unimpressed. "It's not like there were people around to inhabit."

Dean eyed Cas sideways, still clearly in a state of shock. "Cas, could...you be inside a dinosaur?"

Cas shrugged noncommittally, and Sam was drawn in despite himself.

"I didn't know angels could inhabit other species!" Sam said excitedly. "I didn't even think to research it, it just didn't occur to me...how do you get them to say yes to being a vessel?"

Cas looked around somewhat distractedly, clearly not finding this topic of conversation as interesting as Sam and Dean did. "You can tell," he said simply. "Now, my guess is that Gabriel would be in something big...probably something non-predatory…."

"Wait, Cas, have you ever been inside anything other than a human?" Sam asked. The idea of Cas inhabiting some other kind of lifeform had him absolutely floored.

But Cas ignored the question, striding quickly forward, eyes locked on a big group of dinosaurs gathered at the other end of the lake. Sam noticed that Cas had a subtle hand on the angel blade at his side, and Sam did the same thing, trying to anticipate whatever threat the angel saw and prepare himself for it.

"Can you believe this?!" Dean mouthed, catching Sam's eye.

Sam squinted at him.

"Cas as a dinosaur!" Dean hissed, quiet enough not to get their friend's attention. "Like...just imagine how cool that would be."

Sam nodded sincerely. He had to agree, Cas as a dinosaur would be pretty freaking cool.

It wasn't until Sam almost ran smack into Cas that he realized the angel had stopped. He had a funny, blank expression on his face, and Sam stared at him in confusion, not sure if he should be worried.

"Cas?" Sam asked cautiously.

But then Cas shook himself slightly, blinking sluggishly and forcing his eyes to focus on Sam. "I introduced myself to him," Cas said. "He's this way."

"To Gabe?"

"Yes," Cas said. "But this may be...a bit of a difficult situation. Remember, this Gabe has never met you before. He's never even seen a human. I told him I was an angel, but I'm not positive he believes me."

"Just do the eye glowy thing," Dean said dismissively. "Which one is Gabriel?"

Cas pointed to a towering dinosaur, one with a long neck stretching far above the others. It was a dappled brownish green, Sam thought probably for camouflage.

"That one," the angel said, and forged ahead. Sam and Dean followed Cas up to the dinosaur and followed Cas's suit as the angel gave it a respectful nod.

Then, for a rather long time, nothing happened. Cas seemed to be concentrating intently, and the dinosaur seemed to be...responding? Sam couldn't really tell.

After a few minutes, Sam could tell Dean was getting bored. His fingers were twitching, and he'd begun to fidget slightly. And if Sam was being honest, he was starting to feel jittery himself. Dinosaurs were all well and good, but there was only so long Sam felt the need to look at them.

Sam glanced to the side to say something of that sort to Dean, and blinked in surprise when his brother was no longer next to him.

"Fuck. Dean," Sam hissed, looking frantically around. Dean stepped out from behind the Gabriel dinosaur's leg, looking shaken.

"He's gonna step on you," Sam said urgently, edging a little closer to the tree-trunk sized limb. "Dean, come on!"

"Sammy," Dean said, voice quivering with barely concealed excitement. "Sammy, did you know that dinosaurs are blue underneath?!"

"...What?"

"I think it's for camouflage," Dean said, and he was almost vibrating now. "Like, when smaller dinos look up, they see the blue and they think it's the sky, they don't know they're under a motherfucking giant."

Sam settled for confused blinking.

"This is the best day of my life," Dean whispered softly to himself, and he took out his phone again. Sam stepped forward to grab Dean and physically drag him to safety, sore ribs be damned, and found himself staring in awe at the Gabriel dinosaur's underbelly.

"Wow," he said. "It's really blue, huh."

"Yup."

"If the two of you are finished?" Cas appeared behind them, looking slightly annoyed. "I have a location."

Cas stared at the two humans in confusion. Dean was actually giggling, giggling, although Cas knew if he pointed it out Dean would instantly deny it. And Sam was smiling too, a real smile. Cas wasn't sure what was so exciting.

"Dinos have blue bellies," Dean announced, somewhat pointlessly, Cas thought.

"Yes," Cas answered. "I believe it's intended to be camouflage." At this, Dean poked Sam's uninjured side, smile broadening.

"Was it Gabe?" Sam asked, nodding towards the dinosaur.

"No. I chose a dinosaur at random and stared into its eyes for six minutes, just because I felt like it." Cas paused. "That was sarcasm," he added, just in case.

"It-it was," Dean said, a little stiffly.

"I enjoy sarcasm."

"Yes," Dean said. "I can tell."

"So what did you say to it?" Sam asked. He still looked a little suspicious of the whole endeavor.

"Which human is which?" Gabriel asked, directly into Cas's mind.

He had told Gabriel who he was, and of course Gabriel could see his true form so that hadn't taken much convincing. He had explained that future Gabriel had sent them, and this had taken a bit longer to explain but Dinosaur Gabriel had conceded that it did in fact sound like something he would do. Cas had then had to explain that Sam and Dean were actually intelligent lifeforms, and that they had also spoken to future Gabriel and had been sent back with Cas to help him. Gabriel had laughed at first, thinking Cas must be kidding, but Castiel had finally managed to convince Gabriel that people had been part of God's plan all along, and it would only be a few hundred million years before human beings would be all the rage.

Cas squinted at the Winchesters, trying to find differences between them that Gabriel would appreciate. Cas had had a hard time telling Dean apart from the other humans when he had first met him, and they still all looked disconcertingly similar to Cas, but he knew even he had much more experience identifying different humans than Gabriel did. Gabriel had never even seen a human before today. He didn't think Gabriel would appreciate, for example, that Sam was a bit taller, or had longer hair. Both of them must look impossibly tiny to a huge dinosaur, and Gabriel had likely never seen anything with hair before.

"Sam was supposed to be Lucifer's vessel," Cas finally communicated to Gabriel. "Dean was supposed to be Michael's."

Cas thought that even Gabriel would be able to see this, they were, after all, family. Sure enough, he felt Gabriel give him a small mental nod of understanding.

"Introduce yourselves," Cas said quietly to the boys. Gabriel already knew who they were at this point, but Cas thought it might appear more polite.

"To that dinosaur?" Sam asked, eyes wide.

"That dinosaur is Gabriel," Cas said patiently, still feeling like Sam perhaps wasn't entirely getting it, "so yes."

"I'm Dean," Dean said. "You're cool. I like that you're inside a dinosaur. You should tell my buddy Cas to go inside a dinosaur too."

Cas closed his eyes softly.

"What did he say?" Gabriel asked, and Cas relayed the information, carefully excluding the bit about him trying to inhabit a dinosaur. Gabriel nodded, stretching down his neck to Dean's level.

Dean froze. "Cas, he's looking at me, oh my god, a dinosaur is looking at me!"

"I'm Sam," Sam said awkwardly, and stiffened in turn as Gabriel cocked one huge eye towards him.

"Okay, little bro. Really little bro. Hah. The plant is that way. Watch out for the Leviathans."

It was Cas's turn to freeze. "The...the what?" This wasn't good at all.