**Fluff Warning**

BORN ON WINGS OF STEEL

Aien sat on the window seat of the Men of Letters bunker Library, her legs bare thanks to the shorts she wore, and a sports bra being the only thing on her chest. She had one knee up to rest her arm and book on while the other kept itching at spots on her wings. Her wings where not hidden today, and hadn't been for a few days. As long as Sam and Dean had been taking care of a werewolf pack in Michigan. They were due back sometime in the next two days and she was taking advantage of the privacy by allowing her very itchy wings to have some air.

She really hated moulting. She supposed it was just something all angels went through, she'd never actually asked any of the angel's she'd met. Usually because she'd been distracted at the time. Another itch came from her wings and this time it wasn't in a place that she could reach. Aien threw down her book – she'd had a hard time concentrating on it anyway – and let out a cry of frustration before yelling "I bloody well hate these stupid things!" as she stood up. Good thing about the Bunker was that most rooms where large, spacy and tidy which for her meant she could stretch her wings a full length. Like she did now, and began to flap like an irritated bird. It was a weird sensation, mostly because she didn't get to do it often. It was like suddenly having four arms. More feathers littered the library floor as she flapped in frustration, but the movement relived most of her itch. At least it was only the last few days of moulting, which was why it was so unbearably itchy, but meant the only feathers that fell from here where the smaller less important ones.

She folded her wings back into her by a fraction, and heard a cough behind her. Shit, had the boys come home early? She never did like to be caught with her wings out… it felt too personal.

She turned and found Castiel standing in the library door staring at her with wide eyes, his mouth open by just a fraction as his gaze raked her silver feathers. Aien sighed "Oh, hey Cas'" for some reason she didn't mind him seeing her wings so much… maybe it was because he had a set of his own.

He continued to stare mouth agape.

"Uh… Castiel?" Aien asked a little louder. Why was he staring so hard? It wasn't like he hadn't seen them before… though she tried hard to forget that night he had seen them. Maybe since it was during the time he'd been quite insane he didn't remember?

He didn't seem to snap out of his staring until Aien walked up to him and snapped her fingers in front of his face. "Yo, angel-face, wake up!" she said with a smile.

Castiel blinked and finally looked at her face with a very slight crease between his brows. "I don't understand, I am awake?"

"Yeah but you kept staring and not answering so I was asking if you'd fallen asleep with your eyes open" she replied with a grin. She loved his cluelessness. It was cute, and she was glad that after everything he'd been through her best friend could still be quite the innocent.

"Well I had not… I was just surprised to walk in on an intimate moment…" he looked a bit embarrassed.

Aien frowned "you didn't want in on an intimate moment Cas."

He frowned too "but… your wings?"

"I'm moulting feathers Cas and it really itches. I was just trying to get rid of that itch because it is driving me absolutely fruit loops crazy!" she paused her miniature rant and looked at Castiel from the side "hey I've never actually asked but do full angels get the moult thing or is it my curse as a hybrid?"

"Oh" Cas said "no, all angels replace their feathers once every hundred years. I am surprised you have had one-"

"-I get one once a year Cas… like a bird" Aien said with an amused raise of her eyebrows.

"Oh…" he looked uncomfortable.

There was a tense moment, and then Aien realised why he might be uncomfortable. "Uh, Cas… why did you think it was an intimate moment?"

The angel shifted uncomfortably on his feet, glanced at her and then away again. "Well… it is uh… normally you see angels only show their wings to, well, people they are intimate with…"

"Oh…oh" Aien's eyes widened, but she couldn't help the wicked smirk that grew on her face. "So this is… is kind of like if you walked in on me in my underwear or something?"

Castiel looked at her face now and said "It would be a better description to say it is similar to my accidentally discovering you nude."

"That bad?"

"Worse actually, I just could not think if a better description. Your wings are an extension if your soul Aien, which is why they are so considered a very intimate part of you…"

"Ah…well… I apologise for making you uncomfortable."

"No its okay, you don't know the formalities of angels" he assured her with a very slight smile.

"Just while we're on the subject, is there anything else I should know?" Aien asked over her shoulder as she made her way back to the window seat of the library. After some hesitation Castiel followed her into the room and perched on the very edge of the seat at the opposite end.

"I don't believe so as you are not actually an angel, in fact your blood is more human than angel even if you do possess some of our abilities-"

"-yeah but I know them then I won't accidentally make you uncomfortable."

He seemed surprised at her reasoning, and shifted uncomfortably again when the tip of Aien's wing accidentally brushed his arm. "Uh, okay" he said "well, it is also considered a high demonstration of trust and intimacy to allow someone to touch your wings as they are very sensitive…" he glanced at her curiously "have you ever let anyone touch your wings?"

Aien cleared her throat "no, I haven't. I mean I was considering asking someone to help me reach this goddamn itch – seriously I'm going crazy – but if that's not supposed to…"

"-Aien, you're not an actual angel and you were raised by humans on earth where there are no rules for wings…" Castiel reminded her with a frown.

Aien stared at him and bit her lip. "Yeah I know that Cas… but you're the only other person in the bunker at the moment, which means if I was to ask someone to help me, it would me you."

Castiel looked alarmed and then turned away from her.

Aien didn't blame him, he was tense enough when Aien hugged him that her asking him to do something considered so intimate by angels was probably very far out of his comfort zone. She fished another book from the floor around the window seat and was about to settle down and start to read again when Cas said in a soft voice, so quiet she almost didn't hear "I'll do it."

Aien nearly dropped her book. "Say what?"

Castiel frowned "What?"

"No" her lips twisted into a smile "I mean repeat what you just said because I'm not sure what you just said."

"Is there something wrong with your ears?"

"No Cas, just say what you said again" she rolled her eyes, smiling softly.

"I said I would do it… if you wished. I know it can be very uncomfortable this moulting, so if it would make you more comfortable I… I am willing…" he wasn't looking at her, his eyes kept darting around the room for anything else to look at.

Aien frowned "but I… I thought that was considered intimate for you? I mean it would probably make you uncomfortable Cas and I wouldn't ask you to be uncomfortable." Even as she spoke an itch appeared on her right wing, the one that kept accidentally brushing Cas's arm, and she bent to try and rub her fingers on the itchy spot but couldn't reach.

Castiel noticed her, but she wasn't watching him, which meant she was surprised when suddenly his fingertips put pressure on the spot that was itching and he began to rub very lightly on the soft silvery feathers. Aien cast the angel beside her a glance to make sure he was okay, but he was watching her with a kind of curiosity. She gave him a shy smile, which he returned after a second, and seemed to encourage him to increase the pressure on Aien's wing. He rubbed in a circle and Aien sighed into his touch feeling the first real relief of the itching for over a week.

Castiel turned so he could reach her better, his eyes still watching her for any sign that she wanted him to stop, but the only look she gave him was an encouraging smile so he continued. Aien turned so her back was to him more, her wings seemed to stretch out of their own accord to allow Castiel access to a larger surface area. Seeing her wings spread seemed to boost Cas's confidence and he started to mirror his actions on the other wing with his spare hand – making Aien moan. She opened her eyes again when the sound left her mouth, surprised, and Castiel froze in his actions.

"Uh… sorry" she mumbled shifting a little uncomfortably. "I just didn't expect it to feel so… nice?" It was more than nice, it felt fantastic. Like a massage on muscles like rock. Or that first breathe of air after holding your breath underwater, or…well, like sex. Which was an odd thought.

Castiel didn't say anything for a few minutes and Aien thought that he would leave, so she was pleasantly surprised when he asked "would you like me to stop?"

She thought about it, worrying her lip. "No, please continue. This is the best I've felt in weeks."

With that little encouragement Castiel's hands started to move amongst her feathers again, a little more firmly, and he even started to remove the looser feathers that had not yet fallen and where causing her irritation. Aien managed to keep any more awkward noises, right up until his hands reached the spot on her shoulders where the feathers turned fluffier and the wings joined her back. He curled his hand so his fingertips where pressing into the underside of the joint while the ball of his hand and the thumb pressed into the back. Aien couldn't help but gasp and muttered "fuck…" and this time Cas didn't stop.

Well he didn't stop until a familiar voice asked "is this some kind of freaking angel sex thing?"

Castiel's hands dropped from her immediately and he stared at Dean with wide eyes. The oldest Winchester was standing in the library door, his shirt was ripped but there was no blood or scratches on the exposed skin, but he was glaring between Castiel and Aien. While the angel was clueless understanding exactly why Dean was reacting like that and not with the humour he might have used if he'd caught Sam and someone in that kind of position Aien knew exactly what was going on.

Ever since her attack all those months ago Dean's already overprotective big brother role towards her had gone up by at least a thousand points. It would be almost suffocating if it wasn't kind of adorable at the same time. Sam was no different. Apparently this overprotective attitude even extended to the angel they considered family.

Aien decided to save Castiel from having Dean tear him a new one. "Don't be stupid Dean, Cas was just helping me out with the stupid wing thing." She said with a roll of her eyes "looks like that werewolf nearly got your heart though, did the hunt go that badly without me?"

Dean scoffed and dropped his bag to the floor, then eyed the pair in the window seat again. He looked like he was about to say something else when Sam suddenly appeared from down the hall, saw Aien and Cas and nodded to them. "I told you he'd be with Aien" he suddenly said to Dean.

"Yeah thanks for coming back to tell us she was fine Cas" Dean said voice thick with sarcasm.

Cas shifted uneasily "I was… distracted."

Dean snorted "Yes I saw that."

Sam frowned "what'd you see?"

"Nothing" Aien growled and glared "Dean's just overreacting because Cas was helping me out with itchy wings."

"Didn't look like that from where I was standing."

"Yeah but your always standing with your mind – in the gutter." Aien fired back.

Sam gave his brother a look "she's right. Porn has permanently damaged you so you can no longer distinguish between reality and porn."

"Told ya" Aien said standing, her feathers fluffed like a bird and more bits of fluff littered the floor around her drawing everyone's eyes. "I'll clean those later, just let me go shower" she sighed, the water always soothed her wings during moults.

No one spoke until they had heard the bathroom door down the hall shut. Dean looked at Cas. "Dude, that's my fricking sister."

"Dean" Sam frowned at him.

"No wait Sam-" Dean held up a hand to stop the younger brother and Sam gave the angel an 'you're on your own' look. "-look Cas, I know you and Aien have a… well a thing. I don't know what it is, but I just want you to remember that she can be a bit delicate after that attack."

Castiel – who had been watching Dean with a wide eyed innocent expression (something Sam wondered if he'd done deliberately or not) – suddenly scowled and stood, hands clenching "what attack?" he asked, his voice a few octaves lower than it usually was.

Dean and Sam frowned – they'd assumed the angel remembered – but before they could reply Aien suddenly re-entered the room and scowled at them. "Alright which one of you used the last of my shampoo?" she asked holing up the bottle accusingly.

Dean and Sam paled a little knowing she was weirdly protective of her shampoo (they supposed it was a girl thing). "Must've been Sam and his luscious locks" Dean said hurriedly trying to exit the room.

"I-what?-no!" Sam protested with wide eyes trying to put a desk chair between Aien and himself.

Aien, trying not to laugh at their scared reactions, threw Castiel a wink.

Title based on the song Icarus (Born on Wings of Steel) by Kansas