Learning to Fly, by Pink Floyd.

He walked up to the Bunker door, and stared for a brief moment at the roses which had sprung up around it. They hadn't been there this morning. He didn't pay them much attention then – although in the years to come, he watched Cas water them every morning – because Cas wasn't waiting for him when he opened the door.

As he it behind him, he heard music start up, soft drums coming through the walls. He started off for the Cassette Room without a second thought. His footsteps echoed on the hallway floor, and a gentle smile spread across his lips in the dim light at the thought maybe Castiel was waiting for him after all. A joking, 'Angel, I'm home,' died on his lips when he walked through the doorway.

Cas was standing in front of the window pacing, profile silhouetted by moonlight from outside. When he heard Dean, he turned to face him with a slow, sure smile. Only the slightest twitches in his expression hinted at – was that nervousness? "Dean," he said warmly, and the sound of his voice ignited something deep inside of Dean.

Dean strode forward to meet the angel, cupped his face in both hands and crushed their lips together. Somehow their afternoon of separation felt, in that moment, like years. The press of their bodies together was sweet as Cas wrapped his arms around Dean's shoulders and pulled him closer. A flash of blue out of the corner of his half-closed eyes notified Dean that Cas was wearing the leather jacket Dean had given him. "Hey, Cas," Dean murmured, pulling away slightly to stroke Cas' cheek.

"Hello, Dean." Cas said, and with that, he dropped to one knee.

Into the distance, a ribbon of black

Stretched to the point of no turning back

A flight of fancy on a windswept field

Standing alone, my senses reeled

Dean stared down at him, the stillness around them seeming to ring as he waited for the impending realization to crash down. Cas looked steadily back up at him, blue eyes practically glowing in the dark room.

"I… trust I'm doing this correctly," Cas said. A pause. "I've been thinking about it for a while. About how, it seems almost laughable, to be bonded together as we are, grace and soul, and this final, mortal custom dictates that we're apart. And how I want to be bonded with you in every conceivable way. I also thought about how it seemed, as traditions go, a beautiful one, even if it did have its origins in considering women as property…" Cas trailed off, and then steeled himself. "And I believe this is the part where I ask you to marry me."

Dean's jaw dropped, and he couldn't say anything. Didn't even want to say anything. He just wanted this moment to stretch on into eternity, a marker of how far they'd come, and for what they'd fought for. He wanted to stare at Cas' hopeful, shining face forever, listening to Pink Floyd on repeat until doomsday.

"Dean?" Castiel asked, tongue darting out to lick his lips. "I think you're meant to say some-"

Dean fell to his knees in front of Cas and cupped his hands fiercely on either side of the angel's face, because oh, oh, oh. Right. He'd probably want an answer. And so before the ringing had quieted, before the surprise had died down, before he had fully processed the magnitude of fucking everything –

"Yes," he growled, kissing Cas like a drowning man might gasp for air. "Fucking yes," he whispered into the space between Cas' parted lips. Yes, the swipe of his tongue screamed. Please, begged his fingers as they scrabbled for purchase, for something solid to hang onto, to prove it was real. God yes, he thought as Cas moaned against his lips. And their foreheads pressed together when they broke apart murmured finally.

A fatal attraction was holding me fast

How can I escape its irresistible grasp?

Can't keep my eyes from the circling sky

Tongue tied and twisted, just an earthbound misfit, I.

Cas swayed slightly against him, hands coming to grasp at Dean's wrists, holding him tightly. Which was just as well, because Dean felt like he might fall down at the touch of a feather. "You know, I'm aware this won't be easy." Cas said. "Things rarely are."

Dean blinked. "Jeez Cas, way to kill the mood."

"My point," Cas continued as if Dean hadn't spoken. "Is that we have endured the worst, you and I. We've been brutally tortured, fought bloody wars, doubted our own strength- and saved each other." Dean was fighting to make another sarcastic comment, but he knew Cas was only speaking his mind. He felt pinpricks at the back of his eyeballs, tears threatening to spring loose. "In that past year, you've also taught me about humanity. That the greatest challenges do not always come with black eyes."

"You rehearse this or something?" Dean asked weakly.

Cas smiled a little at that. "I must confess that I did. Dean, you taught me that life is a series of ups and downs, but that we will – and deserve to – come out on the other side. Perhaps not unscathed or unchanged, but together." Dean grit his teeth at the sheer sentimentality, the big words and the weighty statements of it all – but inside, it warmed him, too. This was Cas talking from the depths of his heart, and he loved Cas, and though his monologues were hella long sometimes, he'd always listen. Cas looked up into his eyes, and hesitated before saying, "I am aware that this endeavor may have unforseen consequences and trials." Dean opened his mouth to say something to break the seriousness of it all, anything, but Cas cut him off. "This is just another way we will have to learn to fly."

Ice is warming on the tips of my wings

Unheeded warnings, I thought I thought of everything

No navigator to guide my way home

Unladen, empty, and turned to stone

Dean smiled, and the tears were free now, rolling, rolling.

"You know, I listened to the Tom Petty song before I went to heaven. It was beautiful, Dean. To think that when you spoke to me that day in the woods, I didn't know what you were talking about," he laughed a little. "I heard this song-" he gestured around, and Dean grinned. He loved this song. When he'd been hunting alone and hadn't had enough money for a motel room, he'd had to sleep in the Impala. He'd fallen asleep to this song most nights. "It was on the radio in a Gas 'n' Sip while we were on a hunt a while back. It just spoke to me." Dean thought if he smiled any harder, his face might split apart. "And it made me think of you. Of our journeys."

"I fucking love you," Dean cut him short and once again closed the distance between them, seeking the cool, full press of Cas' lips. Cas gave in easily and sighed, winding his fingers through Dean's hair.

A soul in tension that's learning to fly

Condition grounded but determined to try

Can't keep my eyes from the circling skies

Tongue tied and twisted, just an earthbound misfit, I.

"Dean," Cas broke away, a little breathless. "I didn't finish. And I believe it's customary to have an exchange of rings."

Dean closed his eyes for a moment, letting it wash over him.

Cas kissed his eyelids gently and said in a low voice, "Dean, this is my way of promising you. Forever." When Dean opened his eyes, Cas was holding two black metal rings, a little scuffed up around the edges.

"I got them from an antique pawn shop, but it was operated by white witches," Cas admitted. "They're beat-up, but magically unbreakable. I thought that might be useful given-"

"I love them," Dean said, reaching out to touch one of them and then pausing, hand hanging in midair. "They've got Winchester charm," he said jokingly, and then looked up at Cas. "You know, you don't have a last name."

Cas' lips twitched, but instead of commenting, he slid one of the two rings onto Dean's finger. Dean watched it with a fierce happiness kindling inside. "I think that means you're going to have to take mine."

Cas looked up at him, and Dean saw he wasn't the only one crying. "I'd be honored," Cas said. With that, Dean took the ring which still rested in the palm of Cas' hand, and pressed it onto his ring finger. Cas grinned and wiped a single finger across Dean's cheek. He collected a tear that was about to fall and lifted it up to the light, studying it like it was a piece of heaven.

Above the planet, on a wing and a prayer

My grubby halo, a vapor trail in the empty air

Across the clouds I see my shadow fly

Out of the corner of my watering eye

A dream unthreatened by the morning light

Could blow this soul right through the roof of the night

"Sam assured me many times you would say yes," Cas said into the stillness. "But I knew anyway."

"Smug bastard," Dean muttered, planting a kiss on Cas' forehead.

"I suppose so," Cas said. "I like to think that, even back in that barn, I knew that there was something between us, something different. Even before I knew its name."

"Who gives a damn whether we knew then or not," Dean said. "We know now." After a moment, he said, "Sam knew about this?"

"He was my confidante," Cas admitted.

No wonder Sam had been acting so weird. "I'm glad we have you, Cas," Dean said. "Glad I have you," he added, running a finger under Cas' Adam's apple to feel it bob. "And I promise you, that every day until I die, I will love you, and we'll learn how this whole life thing works together, and every night, I'll-" he leaned forward and whispered in Cas' ear.

"I think you just found your wedding vow," Cas murmured, a tad more reverentially than Dean might have expected given the filthy jist of what he'd just said.

"You can count on it," he answered with a grin.

"There's one more thing," Cas said. His fingers curled on Dean's shoulder, resting above where his handprint lay. "Your body is marked as mine with a piece of my grace." Dean gazed into his eyes, shaken by the naked honesty that lay there. "I want you to mark mine."

Dean frowned, but before he could stop to ask about logistics, Cas was lifting Dean's hand to his chest. Over his heart. Cheesy sonofabitch, he wanted to say, but the words didn't quite make the cut. He flattened his palm, feeling the soft thumping he'd grown to need to hear at night. Cas' eyes flashed blue, and Dean felt a jolt of electricity run through his arm, something wild and untamed. Light swirled around them and he felt Cas' skin burn like fire.

When it was done, he pulled away and stared. The white scar of his hand rested across Cas' chest. Cas looked down at it with something resembling awe.

"I hurt you," Dean said, his fingers lifting to trace along the scar.

"Don't be sorry for this, Dean. Never be sorry for this. We've changed each other, you and I. And this is a mark that we belong together."

Dean stared up at him steadily. "It's my promise." Already, it was starting to seem like the scar belonged on Cas' skin.

There's no sensation to compare with this

Suspended animation, state of bliss

Can't keep my mind from the circling skies

Tongue tied and twisted, just an earthbound misfit, I.

They stayed there until the sun started to rise, tears shining on their faces, half-tangled together, the silence punctuated only by soft kisses and sighs. Cas said as the morning light began to fill the room, "This is what flying feels like." He broke into a smile.

Dean led him wordlessly down the hallway and into their bedroom. "Yeah," he whispered as he sealed their promises with a kiss.

I'd like to thank each and every one of you for sticking with me through this journey! Even if I haven't replied to your reviews, I've read them all, and they've made my day and encouraged me, so many times. If you've been reading up til now, I'd love to hear what you thought of the story and of the ending.
If people really want it, I'd add an epilogue, but I feel like it ties in better with the beginning this way. It's made me so happy to be able to spin a story for y'all. I'm sad to end this, but also so very happy I wrote it.
Thank you for your feedback, your song recs and your fellow fangirl-ship. *Salutes*
~BadassCompany
P.S. I'm working on a seriously smutty multi-chapter fic working within canon - essentially, all the times Cas and Dean have sex. Subscribe to my author page if you want updates. ;)