Chapter Text
Cas has to tow Dean out of the passage of doom with two legs wrapped around Dean’s torso and six of them dragging them both along. Dean’s eyes squeeze shut so he doesn’t have to watch the stone move past them—so he doesn’t think about how there’s no water in here to ease along his gills.
But Cas isn’t even breathing hard, his jets of water steady and comfortable, as he pops Dean, a fully grown-ass adult mer male, back out into the cold, deep water with an easy yank of those strong, incredible, sexy legs.
Holy shit.
If they hadn’t been floating smack in the middle of the deep, open ocean with nothing for whole songs around them but cold, stone reef wall—and if Dean hadn’t been so tired that his tail’s dragging—Dean thinks that someone would have gotten himself fucked right there.
On the day the egg hatches, squirming and bobbing around and around in Cas's cave until Dean's worried it's going to roll right off its stabilizing bed of sand and bang into the sides, Cas is so nervous he’s plastered against the back wall like a starfish. His eight legs are spread out and shaking like he’s holding against a stiff tide, gone nearly the color of dirty sea-foam.
Dean rests his arms on the ledge of the cave, his tail poking out behind him into the open ocean. He made sure his air sac is full just right, so he can hang out and hover here as long as he needs to. “Hey, it’ll be okay. Jack’ll be fine, look—he’s trying to get out,” he tries to tell Cas. As time has gone on, the egg has stayed the same brilliant pink, but the baby’s glow has gotten less and less bright—which really, really scared Dean until Cas told him this was normal, that newly-hatched cecaelia don’t glow at all. Which makes sense, but it means that now Dean’s straining his gaze to see his mate and their egg inside the cave.
“But what if he's sickly?” Cas asks, in a whisper.
With a squirm of guilt, Dean wonders if Cas was thinking that all along, or if it was Dean's question that put that into his head. Seas, he wishes he could just swim in there and hug him. Hug them.
But at least he has an answer for Cas.
“Then we move closer to the colony. I'm sure we can find you a cave nearby where you can keep him protected until he gets bigger and stronger, strong enough to mind himself. And you know me, I can sleep anywhere. Sam'll help,” Dean adds. Cas hasn’t let any other mer anywhere near the egg yet—which Dean gets. Still, Sam practically lays an egg himself every time Dean mentions something cool about the egg—how big it’s gotten, and how the membrane isn’t so soft anymore, or seeing the first curling shadows of all of the baby’s little legs. “He’ll be all weird and nerdy and excited about it; he says no mer has ever seen a baby cecaelia. Bobby and Rufus would make space for him too—clear out Rufus’s old nest for us, probably. They'll just be grouchy.”
Cas’s wiggles settle a little. “From what you say, they're always grouchy.”
“Yeah, Cas, that's my point,” Dean says firmly. “They aren't gonna be weird about it. Or... well, any weirder than usual.”
Cas squints suspiciously at him, but some of the pathetic grey color of his nerves leaves his bottom half and his mantle stops fluttering.
It goes pretty quickly after that—the egg’s membrane finally rupturing with a faint, anticlimactic little pop, so soft that even Dean’s sensitive ears barely catch it.
Not that he could have missed the thin, faintly glowing pink jelly spilling out onto the surface of Cas’s cave, soaking into the sand-bed, or the tip of a sand-colored tentacle poking vertically out of the top of the opening, like the spire finger of a staghorn coral.
The rest of the membrane rips open as the narrow leg wiggles around, peeling back easily, and the baby that Cas already named Jack uncurls himself out of the jellyfish-thin shell of his egg—
Out and out and out, all long limbs, sticky, pale skin, and shockingly alert gaze.
Uh. Okay.
That is definitely not the tiny, wobbly baby fry with a round, plump face and little, miniature tentacles that Dean was imagining.
Nope. What uncurls out of an awkward knot of legs has a long, clever face, a slender torso, and a mantle the color of sand. Even from the opening of the cave where Dean is hovering, he can see that the newly hatched cecaelia shivering his way upright on his eight legs, spreading his sticky mantle, has Cas’s blue eyes.
Except sure as the seas he’s not a baby.
Nope. Jack looks for all the world like a juvenile—and not a young juvenile, either. Once he has his legs settled underneath him, his mantle still rippling uncertainly, it’s very clear: he’s got narrow shoulders, and he can’t quite get himself all the way coordinated yet and has to steady himself against a wall with one of his legs to keep himself from toppling, but he’s only a little bit smaller than Cas.
Cas doesn't seem surprised by this, though, even though Dean’s staring with his mouth open, not sure if he needs to dive into the cave to help—screw suffocation anyway—or what he’s supposed to be doing here. Instead, Cas rushes close with two tentacles full of already-open shellfish, another two legs carefully poised and hovering around himself.
(Dean only realizes later that they were positioned that way to help propel Cas back and in front of Dean, prepared to block the way just in case the young cecaelia was aggressive. Dammit, Cas.)
But Jack looks down at the treats, and then reaches out one leg to delicately take them from Cas. “Thank you,” he says, in slow, clear speech.
Dean bubbles so hard in shock that he almost sinks before he catches himself on the edge of the ledge and pulls himself back up. What the—
But both Cas and Jack have turned towards the mouth of the cave, where Dean’s hovering and making a bubbly idiot out of himself. Then Jack raises another of his legs, holding it up into the air. “Hello,” he announces, waggling the tip.
All the while, Jack's arms remain still and limp by his sides.
“Uh... hi,” Dean says, finally. Because what else is he supposed to say?
He can talk? The baby can talk?
“Are you Dean? I'm Jack!” the young cecaelia announces, all in a rush, like he came up with this idea all on his own rather than Cas having given him the name. The leg Jack’s holding up wobbles from side to side—waving. His suckers are as pale as a flounder belly, and faintly tinged with the same pink as the membrane of his egg—the wrapper now crumpled around him like kelp. “You have a tail! I could hear you talking. And singing. I like the singing!”
Cas turns his head for just long enough to raise an eyebrow at Dean. Cas can’t see Dean’s blood-scales turn red from where he is, Dean’s almost sure of it.
So what if Dean was singing to the egg when it was his turn to keep watch? He didn’t know that Jack would really be able to hear him in there!
“Hello, Jack,” Cas says, very seriously. “Yes, this is Dean. I’m Castiel. Cas,” he corrects, and Dean thinks his heart might just break from love.
“Are you my fathers?” Jack inquires, then looks down at the scallop held in one of his legs with distracted interest. “Oh, this smells good.”
“Yes,” Cas says as Jack happily crams the scallop meat into his mouth. When Dean looks over at his mate, Cas is smiling so widely, beautifully widely—the membranes of his eyes lowered sweetly with emotion and his coloring gone precious-coral bright again with delight. “Yes, Jack, we are.”
Jack loves evening reef-watching nearly as much as Cas does. He's not coordinated enough yet to catch most reef fish, not even to play with them—probably much to the relief of the spotted yellow boxfish they’re studying, and definitely to Cas's relief, since they're poisonous and Jack puts everything in his mouth—but it's not uncommon for Dean to find his boys around here, gleefully watching the little colony they've taken to.
Cas didn't get to watch the boxfish babies hatch last cycle, but the two of them are definitely enjoying the batch of tiny, speckled juveniles growing up now: both Cas and Jack belly-down on the reef floor with their legs half-buried behind them, heads bent together, their eyes on where the boxfish are suspiciously wiggling their weird, awkward way closer to the chopped-up bits of rock shrimp that Cas and Jack must have brought to feed them.
Seas, what the sight of it all does to Dean's heart: his weird, nocturnal cecaelia family, hanging around sleepily in the late afternoon reef with their many clever legs camouflaged to the color of sand, bonding over their little boxfish pets.
(These are pets; the clownfish near Dean's ledge aren't. There's a difference. Really, Cas.)
“Dean’s going to take me swimming today!” Jack probably thinks he's whispering, but he's not very good at that yet, either. Kid should be glad he can camouflage, because he is not quiet. “He’s so fast.”
“Yes, Dean's very good at swimming,” Cas says, so neutrally that Dean almost snickers. They’re probably never going to agree on the swimming thing. But Jack loves to swim, so there. “Are you sure you want to go all the way to the volcano? I know it's very tiring.”
“Yes! It's so far, but he takes me to eat the best stuff,” Jack says, excited. “He says he knows where maybe we can find scallops!” Then he wilts, his shoulders drooping and his legs and mantle going a little grey.
Dean doesn't quite groan. Ah, shit. Nope. Kid is the happiest creature that Dean thinks he’s ever met, but he can't keep a secret to save his whole life.
“Jack?” Cas says, frowning at Jack's abrupt color change and pushing himself upwards enough on his arms that the sand stirs around his legs and he darkens a little out of his camouflage. The boxfish swirl away from the hint of motion and shadow. “What's wrong?”
“We were going to bring some back for you,” Jack confesses, his legs greying further. “It was supposed to be a surprise.”
“I'll still be surprised,” Cas answers, with a soft chuckle, and he settles back down on his elbows. “I never know what you two will find out there.” The tip of one of his legs curls upwards and pokes gently at Jack’s side, making his color brighten again. “You be careful, though, all right? You can't swim too hard.”
“Or my organ heart will stop, I know, Cas,” Jack says, just a little impatiently. (Right, like it didn't stop Dean's single solitary heart when Jack started to jerk and sag in the water the first time Dean pushed him too fast and Jack couldn't keep up. Dean ended up swimming straight home with their son clinging to his back, even though Jack assured him he was fine and his heart had restarted. Fucking cecaelia physiology, seriously.)
“But swimming is fun,” Jack adds. “And swimming with Dean is the best. Sam's too pushy and strict about it—he says I need to use my arms more. But I don’t know why.” Jack sighs. “Sam’s weird about everything,” he mutters.
“Jack,” Cas says. He’s trying to be stern. But the back of his mantle is rippling with the effort of not laughing.
“Well, he is.”
Dean always knew the kid had a good head on his shoulders, right from day one.
(Dean still thinks that Cas should have warned him that Jack was going to come out of his egg a fully formed person and not a baby. But Cas pointed out that of course Jack wouldn’t have hatched as a defenseless infant fry—how would any cecaelia male survive to adulthood then, alone in the deep ocean as most of them are? Dean couldn’t argue with that logic, and since he also didn’t want to get into it again with Cas about how fucked up his species is sometimes, he closed his clamshell.)
“Well, it's getting dark soon, and unlike you two, I can't see in the dark—so if you still wanna go swimming, kiddo, we oughta go now,” Dean tells the backs of his cecaelias’ heads.
Jack, much to Dean's gratification, still jumps whenever Dean sneaks up behind or on top of them without using his echolocation. Cas doesn't anymore, of course—he can hear Dean coming, catch the way the afternoon reef responds to a mer’s presence. Dean's so damned proud of how well Cas has learned to listen.
Cas still can't sing, though. But, well, can't have everything. And Jack’s kind of getting okay at vocalization, so there’s that? Rufus practically chuckled himself into sinking when Jack happily sang the dirty version of the location song for him.
“Oh!” Jack blurts, scrambling back upright in a clumsy flurry of sand and legs that sends the boxfish diving for cover in the coral. “I have to go get my necklace. I'll be right back! Don't leave without me,” he says, so stern, and so much like his cecaelia dad that just watching him makes Dean's scales practically ache with familiarity and happiness.
It's weird to think that Cas worried that Dean might not recognize Cas in Jack. Sure, the kid is not Cas's, of course—his native colors are a lot lighter, and when he's not camouflaging, his legs, surprisingly, are closer to the color of Dean's hair than Cas's dark blues and blacks. His underside has stayed a delicate, pale pink that always reminds Dean of the glow Jack put out when he was still in the egg—he didn't outgrow that.
But those blue eyes of his? Unmistakable. And the way Jack moves through the water, the way he smiles and tilts his head and gives Dean that puzzled, worried, confused look when Dean says something he doesn't get? Cas all the way down to his cartilage.
As Jack hurries off, clambering gracefully towards Dean's home-ledge, they both watch him go.
(Dean will never admit that Sam’s right, that Jack might have an easier time if he used his arms and fingers for things more, rather than just his legs. Bobby’s having a hell of a time teaching him how to write. But Cas peacefully tells them that that’s pretty normal for young cecaelia, because their ‘legs are reflexively smarter than their arms’ for a while. Again: weird.)
“We should tell him that at his age, he doesn't need to wear that necklace anymore,” Cas muses. “He generates enough pheromone to repel sharks naturally.”
“S'okay,” Dean says with a grin, floating closer and letting out enough air to drift to a comfortable flop just beside Cas on the sand. The boxfish, confident as only something with tiny fins and a bright, toxic body can be, have already come back out from the coral shelter, and they start wiggling their way back towards the tempting shrimp snacks. “It’s cute.”
“I guess it is.” Cas pushes himself gracefully out of the sand hollow and back into an upright position, his legs and mantle fading slowly back to his native dark blue as he lets his camouflage go.
He smiles his best smile, the soft, small, proud one, when he reaches out a leg towards Dean. Dean knows what that means, and he's already grinning as Cas silently drops three sweet rock shrimp—these ones whole—into his outstretched hand.
“I'm not a boxfish, Cas, you don't have to feed me,” Dean teases, but he slowly rolls onto his back and pops all three of the shrimp into his mouth whole, chewing luxuriously. Mmm, fuck, they're so good.
(Sam always makes a face when Dean eats shrimp whole rather than just licking up the insides of the shells, but Sam also has to chew special supplementary rock to keep his scales in good condition and Dean doesn't: so there.)
Cas sidles closer, and one of his legs drapes in a sucker-sweet curl around Dean's tail, careful not to impede the flutter of the fins holding Dean steady in the water. “But I like to feed you,” he says, nuzzling closer. One of his tentacles pets gently up and down Dean's stomach, which sure as heck didn't get any padding in the first few cycles of Jack's life—a newly hatched cecaelia puts away enough food to make a humpback proud, it turns out—but is just now starting to go softer and fuller again. “Almost as much as I like telling you you're pretty.”
“Yeah?” Dean murmurs, and rolls onto his side, lifting a finger to tickle at the sensitive edge of Cas’s mantle.
Cas shivers happily. “Pretty,” he repeats. “Beautiful.” One of his legs curves between them and traces around Dean’s mouth. Dean opens his mouth and feels the flutter of a tiny sucker kissing the tip of his tongue—tasting him just as much as he’s tasting Cas. Cas’s voice slides low as an earthquake. “Enticing—”
“I'm back! Oh. Are you engaging in mating behavior again? You did that the last time and we couldn't go swimming,” Jack announces, from somewhere behind them. “I can go away and come back later! Oh,” he muses, at a lower mutter. “But then it’ll be late and Dean can’t swim in the dark.”
Cas’s mantle goes so orange that the clownfish really could mistake him for an anemone, and he pulls his tentacle out of Dean’s mouth.
“Now I get all the completely pointless errands Bobby and Rufus used to send me and Sam on when we were juveniles,” Dean sighs, dropping his forehead onto Cas’s shoulder. “Hey, can we throw him back?”
“No,” Cas says firmly—but there's a wrinkle of laughter that's creasing the middle of his forehead when Dean peeks mournfully up at him. “But we should leave him with Bobby and Rufus when my breeding season comes up again,” he offers at a whisper, leaning close, and Dean grins.
“Yeah?”
“Soon,” Cas promises, and winks—a terrible wink that takes up half of his entire damned face, and seas, oceans, and every body of saltwater out there, Dean fucking loves him.
“Deal,” Dean says happily, and tugs on his mate’s leg for one last playful hug and a big kiss on Cas’s cheek, drawing the tips of his claws lightly down Cas’s back, just enough to make his mantle ripple before Dean lets go. “C’mon, kid, you ready to swim?” he asks, over his shoulder.
Jack nearly smothers him by dropping clumsily mantle-first on top of both of them with a “Yes! Bye, Cas! Let’s go, Dean!”
But Dean wouldn’t have it any other way.
~fin~