A huge thank you to everyone that has been so kind and left me a review for this story... I want to try to reply to each one individually, but RL is a mare at the moment and I'm struggling to keep up with even writing this story, let alone anything else... but believe me, I read every single one, and I thank you all very much. It looks like this story is going to come around the fifteen chapter mark - the next couple will be more about the characters and their relationship before the case element kicks back in... just a warning that the story begins to earn its rating from this point - just a little for a start.

Thank you for reading, following and supporting this story... I'm really blown away. And for the record, I don't own either JKR or Marvel's characters, although I'm going to have a lot of fun with them in the next few chapters.

Merrick xx

This was nice, thought Natasha, a little woozily. Nice to just be held like this, to allow herself to feel protected and comforted for once. She was so used to always being the strong one, the professional. Hard as nails Black Widow who used her body as easily as knife or gun, who used and discarded men and women as the mission demanded, never allowing anything as muddy as emotion to get in the way.

But this one – Harry – he was different. This wasn't about power, or revenge, or the mission. It wasn't about winning trust or acquiring information or gaining advantage; it was just about her, and Harry and the spark that had been there between them right from the start...

"Well Mr Potter, this is a pleasant surprise... is everything quite alright?"

Natasha was dragged back to reality by the sharp, precise Scottish voice behind her, Harry however, didn't move, continuing to hold her firmly.

"Bear with us a minute please Professor. Natasha is a muggle as you know and she's tried side along apparition and the floo network in only a few hours, it's a lot to take in in such a short space of time. She's feeling a little dizzy"

"Oh my goodness yes. Would you like some tea dear?"

Natasha nodded mutely.

"I'll leave you for a few minutes then and sort that out." Natasha heard a heavy door close, and breathed a sigh of relief as the silence returned, finally lifting her head, feeling Harry's hand slide down to rest warm and steady on the back of her neck, under her hair, his thumb tracing distracting little patterns on her skin. She found herself trapped in his gaze, her racing pulse not entirely down to the floo network.

"Natasha" his voice was deeper than she remembered. He tucked an errant lock of hair behind her ear. "Would now be a horribly inappropriate time to say that I really want to kiss you?"

She blinked. "No one's ever actually asked me before..." Never treated her like this, like she was a prize to be courted and won.

Harry ran a thumb over the sensitive skin at the point of her jaw, and Natasha's eyes fluttered shut in response for a moment, tilting her face up to his in unspoken invitation...

It was an invitation he was only too happy to accept, the hand on the back of her neck drawing her closer, brushing a kiss on the corner of her mouth. With soft sigh, Natasha turned her head to deepen the kiss, wrapping her arms around his neck...

"Oh my... do excuse me..."

The moment was lost as the Scottish voice returned bearing a tray of tea. Turning, a little flushed, Natasha came face to face with one of the most extraordinary people she had ever met. A tall thin woman, at least seventy years old, possibly older, dressed in long black robes, with a green tartan witches hat on her head. But in spite of her attire it was her face that caught Natasha's attention first. Razor sharp, not one to suffer fools gladly it struck her that this was not a woman she would wish to cross, but looking closer there was an underlying humour in the hazel eyes that was reassuring.

"Good afternoon to you both. Ms Romanoff – you are clearly feeling much better." Natasha blushed like a guilty schoolgirl and Harry did his best to conceal a grin at her discomfiture. There was something about the Headmistress of Hogwarts that busted even the most hard bitten right back to their schooldays. Natasha's normally inscrutable face was looking distinctly uncomfortable.

"Um... much better, thank you."

In the silence that followed, Harry realised that introductions were needed. "Oh... I'm sorry. Professor McGonagall, may I introduce Natasha Romanoff. Natasha is collaborating with the Ministry on a joint international magical / muggle operation. Unfortunately I can't tell you any more than that at the moment. Natasha, this is Professor McGonagall, my former head of house, now Headmistress of this school.

"It's a pleasure Ms Romanoff... I trust your... collaboration... is proving successful". For once, Harry realised with a grin, Natasha Romanoff was lost for words.

Taking pity on them both, the Professor ushered them back to the fireplace, to a sofa and two armchairs, placing the tea tray on a convenient side table. As the Professor poured the tea, Natasha looked curiously around her. The room wasn't especially big, but had a very high ceiling with carved oak beams. Unusually - as Harry had said - there were no windows at eye level, only a number of long thin lancets, high in the walls, revealing nothing but an overcast sky. The room must be some kind of sitting room she thought, although it seemed odd that there was literally nothing else in the room beyond the chairs around the large fireplace, a table for the tea tray and what appeared to be a blank picture in an ornate frame over the fireplace.

Natasha sat on the sofa beside Harry, accepting her cup from the indomitable Professor. As they drank their tea they talked of this and that. Professor McGonagall updated Harry on events at the school, and made Natasha laugh with a number of anecdotes from Harry's youth. When they had finished, the Professor collected their cups and rose. "It has been a pleasure to meet you Natasha, I wish you all the very best for your endeavors; but I mustn't keep you any longer". Turning, she held out her arms to Harry. "Harry Potter it has been a pleasure as always. I know how busy you are, but please don't be a stranger, come to see us again soon." To Natasha's surprise, Harry happily hugged the elderly woman, who – Natasha's mouth fell open – flicked her fingers at the tray, which rose obediently from the table, and followed her out of the room.

"What kind of school is this?"

"A very unusual one my dear Ms Romanoff"

Harry thanked his lucky stars that UK law did not allow Natasha to carry a weapon, as her hand flew to her thigh, where her holster would normally be located. She was staring at the portrait over the mantelpiece, blue eyes as wide as saucers. Taking pity on her, Harry rested his hands on her shoulders. "Natasha Romanoff, can I introduce you to the person that we came to see. Professor Albus Dumbledore, my friend and mentor, and former Headmaster of this school."

Professor Dumbledore looked at Natasha with undisguised approval. "It is a pleasure to meet you Ms Romanoff. Harry, it is good to see you my friend, but please don't feel that you need to consult with me on some grave matter before you come to see me. A simple chat sometime would be equally welcome." Harry muttered something about the pressures of work, which made Natasha and the professor both smile. "Now, how can I help you today?"

It took Harry and Natasha some time to explain the full story to the former Headmaster who listened carefully, blue eyes keen over his half moon glasses. "This is interesting. This is very, very interesting." Professor Dumbledore summoned a large armchair, and seated himself comfortably to better consider the problem. "Ms Romanoff, would you mind reading the parchment once again please?"

Hesitating, Natasha reminded herself sternly that she was a professional . She had dealt with Hydra, the KGB, Nick Fury at his worst, aliens, psychotic Norse gods and rampaging green rage monsters. She could deal with floating tea trays and figures that wandered in and out of portraits dispensing wisdom and guidance. She retrieved a sheet of paper from the table.

"Monastery of Saint Cynderyn, Llanelwy, North Wales

The nights darken as this year of Our Lord 596 year draws to its close, and I know in my heart that I shall not live to see the birth of another. My life as a Choir Monk of this House is now over, and I spend my final days in the Infirmary among my brothers. Brother Athanasius, the Infirmarer has granted me the luxury of a small writing desk, and on that desk I write this, my final testament.

I have seen much in my long life, and in that time have been warrior, sinner, scholar, servant to those who walk with Kings and now, finally, Brother of this House, from whence I will set out upon my last journey when my time comes. I pray that God will look gently upon my sins, and receive me into his arms.

But I must confess that this dearest hope is also my greatest fear.

For if I am received into the arms of Our Lord, through the gates of Purgatory, how will I then see my old master again, for one such as he will never be received at the Gates of Saint Peter. Perhaps Our Lord will refuse my sinner's soul, and I will find my shade wandering freely with my old master and that brave company, sharing adventures as we had been wont to do, before he chose to follow his greatest friend and King into the shadowlands to await this land's greatest need.

If it is not my destiny to see him again, then I pray (and I hope the Good God will forgive such blasphemy) that my master knows that I did not fail him. That the great treasure that he entrusted to me, the source of all of his mighty power, was bestowed on the isle which was so sacred to his people, to lie in safety, watched over by the guardian spirits of the slain, for I tremble for the fate of this world, should such terrible power fall into the hands of the evil doer..."

When she fell silent. Professor Dumbledore pondered his steepled fingers for several minutes. Natasha shifted restlessly, but Harry, used to the way the his old mentor worked, sat patiently.

"You say that this man – our writer – Brother Caron – joined the monastery at the prime of his life, presumably following the death or departure of his former master. It appears that at some point this master of his entrusted our writer with an artifact or artifacts of great power, which he has secreted in a very safe place."

"And we can assume that it is these artifacts that Hydra are looking for" Natasha shuffled the papers, pondering the mystery. "Especially if they are, as our he says 'of terrible power'.

Professor Dumbledore gazed at them from over his glasses. "Well it's very kind of you to involve me in this, but I believe that between you, you know enough of this tale to piece it together without me."

Natasha looked up at Dumbledore. "'Awaiting the land's greatest need' My knowledge of your mythology is sketchy, but to me that sounds like King Arthur, the Once and Future King." Natasha re-examined the translation for the umpteenth time.

Harry nodded. "It is possible. Emrys is a name commonly associated with the Welsh legends of Merlin, friend of King Arthur. And a wizard of course. But there are other legends of great heroes sleeping until their country's greatest need; and as to what we're looking for, I have no idea."

Natasha rubbed her eyes, it was only mid-afternoon and it had already been a long day. "A great treasure – a source of great power' I can't believe I'm about to say this, but we're not talking about the Holy Grail are we?"

Dumbledore polished his glasses. "It is possible of course, but unlikely. The Grail is no longer... how can I put it... up for grabs. It was found by one of my predecessors several centuries ago, and is far beyond the reach of the likes of HYDRA. It might be helpful to do some more detailed work to establish the identity of this Caron, and if possible to establish a link to Merlin. May I suggest, Mr Potter, that a visit to Branwen may be in order"

Harry rubbed his forehead, already anticipating a headache. "Professor, do you have any idea of the paperwork involved in taking a muggle to the most important and secret magical site in Britain? I don't know if it's even possible." He looked up at Natasha with a weary smile. "It appears that you might be my house guest for a few days at least Tash. This may take a while."

"Who is Branwen?"

Harry shook his head. "Believe it or not but we shouldn't even have mentioned her name in front of you. I certainly can't tell you anymore until I have official permission from the Ministry. It sounds ridiculous, but although I've been given a fair degree of leeway under the Statute of Secrecy, if I go too far I could end up in Azkaban."

"The wizarding prison" chipped in Professor Dumbledore. "Even now it's really not a nice place"

Natasha looked stunned. "Seriously. It's that - serious? You could be sent to prison?"

"Oh yes. The Statute of Secrecy is taken very seriously. Even with our powers there are far more of you than there are of us. Most muggles wouldn't see us as a threat, but it wouldn't take much to light the touchpaper and boom... Could be a terrible mess. Look at all the trouble in America with the whole mutant issue, and believe me, most muggles would be much more freaked out about magic than mutations."

Natasha thought of Bruce Banner and the murderous fury on the face of General Thaddeus Ross, and nodded. "Yes I suppose, thinking about it, it would be so much easier just to stay under the radar. If there's going to be a delay though, I'll need to check in with Fury – he's my boss" she added to Dumbledore by way of explanation.

Harry rose. "And I'd better get the paperwork filed with the Ministry today. You'll probably have to come in and meet Kingsley, 'cos he's the only one that's going to be able to make this happen if anyone can." He turned back to the Professor. "Thank you for your help Professor, will you please give our best wishes to Professor McGonagall, we need to be getting back". He reached for Natasha's hand, and she hung back reluctantly, pulling a face.

"Oh no. Not again..."

Professor Dumbledore chuckled. "Don't worry Ms Romanoff, you will find that you become accustomed to it in time."

Natasha took Harry's hand, and smiled straight up at the Professor, who's painted cheeks flushed, and he dropped his glasses. "Natasha, please Professor"

Dumbledore retrieved his glasses and cleared his throat noisily. "Why thank you my... N-Natasha. Harry, do please bring this delightful young lady back once the mystery is solved and let me know how it works out. I have no doubt that the two of you will once again be saving the world." He turned back to Natasha. "Goodbye my dear. It has been a pleasure."

Natasha slid straight into Harry's personal space, until barely a breath separated them. "I guess I'm riding shotgun again then Harry?"

He smiled slowly – that, and the heat in his green eyes did things to Natasha's pulse rate that no-one had done for a while – wrapping his arms securely around her waist. "It's a tough job Agent Romanoff, but I'm sure you've been trained for worse. Now hold tight."

Natasha wrapped her arms around his neck, resting her head against his shoulder. "I need to remember to wear heels when I'm with you. How tall are you? I guess 6'2" like Cap."

Harry rested his cheek against her hair. "I don't know. I reckon we're a pretty good match. Which reminds me Agent Romanoff. Can I take you for dinner tonight?"

"Harry, we've had dinner together every night since we met.."

His scowl was almost... almost convincing. "Natasha Romanoff. That wasn't what I meant and well you know it..."

She gave him her very best smile. The one that was all sparkle and smolder and long thick eyelashes – she usually ended up wasting it on slimeball criminals, terrorists and foreign agents. It was fun to use it on someone she actually liked for a change. "Mr Potter – are you asking me out on a date?"

Just before he stepped back into the floo, Harry looked back over his shoulder at the picture frame, which was blank – strange because he was sure he just heard a chuckle. "Professor Dumbledore, did you know it's rude to listen just outside the frame" He turned back to the lovely redhead in his arms. "Yes Natasha, I was asking you on a date"

Without waiting for a response, he shouted "Twelve Grimmauld Place" as they stepped back into the green flames.

When her head had stopped spinning, and the ground beneath her feet was stable again, she slid her hand onto the back of Harry's neck, drawing his face down to hers. "Yes" she murmured against his lips. "Yes Harry, I would love to go out to dinner with you".

This was good, thought Natasha, senses reeling as Harry lips finally found hers, teasing her until she surrendered, quickly losing all capacity to think coherently...

Much, much later when they were curled up on one of the sofa's, making out like a pair of teenagers, dazed and breathless, and hopelessly, helplessly turned on; it took all of Harry's willpower to finally break it off, to set Natasha slightly away from him, enchanted by the provocative pout in those gorgeous lips, even more so now than ever.

"Harry!"

He took a deep breath, trying desperately to be even slightly responsible. "I have to speak to Kingsley Shacklebolt, and you have to call your boss or we are going nowhere with this."

She wriggled against him, loving the way his eyes were blown so wide that almost all green had vanished, and the way the rigid line of his jaw betrayed his struggle to rein himself in. When he spoke, she loved the note of desperation in his voice even more. "Natasha, behave, please - have mercy... where you are concerned I have very honourable intentions, but..."

Natasha sighed dramatically. "Not too honourable I hope Mr Potter. OK, you win. I'll go and update Fury, while you go and talk to your owls or whatever you magic types do." She looked at her watch. "It's 16.35, what time do you... want me?"

Harry closed his eyes, resting his forehead against hers, as she sat astride his lap. "You test me woman you really do..." his voice dropped to a rough whisper as he pulled her closer, lips against her ear, making her nerves tingle "And as for my intentions... I ... want you... Natasha Romanoff... I want you stretched out naked on my bed. I want to spend hours..." he ran a single finger down her spine, and she arched against him, gripping his sweater, utterly caught in the spell of his words "... getting to know all of you... exploring every stunning inch of your body – one nerve ending at a time... until you can only writhe... and moan ... and beg... but for now..." he rose abruptly, setting her firmly back on her feet. "...how does seven thirty suit you?"

"...Seven thirty's good." Natasha wished that her voice didn't sound so... breathless, so needy. She was the Black Widow, a professional. She was the seducer, the enchantress with the deadly bite. Instead, this green eyed wizard with the strong arms and the wicked mouth had reduced her to putty in his hands. She should put him firmly in his place. She should draw the line, pull herself together, and regain the upper hand, but she found now that there was no desire in her to do so, only to trust – to break the habit of a lifetime, to follow his lead and allow him to make good on his promises.

Trust. Now there was a luxury she could rarely afford. There were those she trusted. Clint, Cap, Bruce, and once, long long ago, a tall dark haired, dark eyed man as damaged as herself, the one they had called the Winter Soldier. But she had been very different then. Things had been very different then. Now she had choices, options. She could allow this to happen if she wanted to... this was not the KGB ... being the Black Widow, an Avenger did not preclude... this, whatever this was...

"Tasha...?" Harry trailed a finger lightly down her cheek. "Are you alright. You zoned right out there for a moment. You were miles away."

She shook herself, smiling. "I'm fine. Go, talk to your Minister, be quick."

"Make yourself at home. Help yourself to whatever's in the kitchen. There should be more hot water for the bathrooms than even you need, and if you look in the cupboard under the sink in your ensuite you'll find towels and stuff."

Dropping a kiss onto her forehead, he pulled himself together, and headed back to the floo to do battle with Kingsley and the pen pushers.

ooo0ooo

Natasha's phone call had taken less time than she had anticipated. Fury had been in a meeting, so she had had a ten minute update with Coulson, before heading up to her room, where the siren call of the large brass bed had proved too much. Naps in the afternoon were never something she'd needed, but she and Harry had both slept badly at the hotel, what seemed like weeks ago, and, Natasha thought with a smile as she drifted off... with a bit of luck she wouldn't get much sleep tonight either.

She had slept a little longer than she had anticipated, so it was approaching seven twenty when Natasha stood in front of the mirror, eyeing her reflection critically. The black dress was one of her favourites. Ideal for travel, it rolled up into practically nothing in her bag, and always made her feel great. But she had packed in a hurry, and had failed to take into account the particular issues of this dress. While the skirt was a relatively demure two inches above the knee, the dress itself, with its thin shoestring straps, was almost as tight as her catsuit, and, unlike the catsuit's black leather, she had forgotten that the dress revealed the lines of anything worn underneath it. With a shrug, Natasha came to a decision... A few minutes later, she gave a satisfied nod at her reflection, and putting on a pair of black heels, headed for the door, hearing Harry waiting for her in the hall below.

ooo0ooo

Harry took Natasha to a small muggle Italian Restaurant, five minutes' walk from Grimmauld Place. It felt pleasantly normal, thought Natasha, putting on a dress and heels, and holding a guy's hand on their way to dinner. It felt a long way from the Red Room, from Budapest, from superheroes, Gods and monsters.

"This is nice" Natasha chased a stray pomegranate seed from the antipasto salad they had shared as a starter. The Barolo in her glass was warm and smooth, and the smells coming from the kitchen were making her mouth water. "It feels like a ... normal date. Ordinary."

Harry's eyebrows rose. "Ordinary. I'm not sure how to take that."

Natasha played idly with the stem of her wine glass, watching the candle flame reflecting in the deep red depths before taking a sip. "No, ordinary is... good. I don't have much practice with ordinary."

"What about your childhood? How does a little red haired Russian girl end up roaming New York dressed in black leather. Which I love by the way. Please don't think I don't love the black leather. Because I really do."

She chuckled, and shook her head. You are hopeless, you know that? The truth is I was an ordinary little Russian kid, keeping her head down and trying not to draw attention to her unfortunate surname."

"Your surname – ah. I see. You aren't...?"

"Related to those Romanoff's. To be honest I don't know. My mother used to talk about it sometimes at night... when she was drunk. How she should have been a princess... had servants. Instead she had a dead end job in an office, a dingy one bedroom flat and a millstone around her neck."

"It was just the two of you?"

"She didn't talk about my father. Truthfully, I'm not certain she even knew who my father was. I worked hard, did well at school, had a talent for languages. On Saturday mornings I did ballet. I loved my ballet lessons."

Harry smiled, imagining an eight year old Natasha, red hair in a bun, in black leotard and tights. "I bet you were adorable"

"One day just after my tenth birthday, two strangers came to my school. They visited a few classrooms, talked to some of the students – always the girls. Then they appeared at my ballet class a few weeks later. It seemed strange, but I was a child. I didn't really worry about it. In fact I didn't think about it again until the letter came nearly a year later saying that I had been chosen for the Black Widow programme. Growing up in Communist Russia, my mother didn't question. Just packed me a suitcase, and that was that..."

Harry drew her hand away from the wine glass, playing idly with the tips of her fingers. "When we were walking around the cathedral, you said that your own mother wouldn't recognise you now... "

"That was the last time I saw her – the day she kissed me perfunctorily on the cheek and closed the door." For a moment all the years of sophistication and toughness peeled away and she bit her lip, eyes soft and hurt for the child she had still been then. "She didn't even look back – watch me walk away".

Harry's hand gripped hers firmly, thumb rubbing little circles on her knuckle, reassuring. "What happened?"

"Years later, when I was ... released... I went back to see her, but she was gone, and no one that lived there had any idea where she was. Two years ago I asked Jarvis to look into it. Apparently she died of liver failure just after my fifteenth birthday. Nobody bothered to tell me."

"I'm sorry"

"Don't be. I don't have children of my own, but... a friend does. They call me Aunty Nat. All I know is that I would rather die than allow what my mother did. To stand by and let those kids to be taken, to suffer, to be afraid or lonely or taken advantage of ..." She broke off, suddenly flustered, as the waiter arrived with their main course. "I'm sorry. I don't even know why I'm telling you this. I don't tell anyone… not even under torture. This dinner is supposed to be fun and I'm just ..." She took a mouthful of pasta and truffles with a moan of appreciation which almost pornographic. "Oh my God that is incredible"

Harry's eyes darkened. "As a wizard and a gentleman, I have to warn you that if you keep indicating your approval like that Ms Romanoff, I am going to be forced to take you home now… before dessert. And that would be a shame because the desserts here are amazing".

Natasha took another mouthful of pasta taking in a few leaves of rocket, and half a cherry tomato with it, closing her eyes for a moment with an air of rapt enjoyment that made Harry's breath catch. "That's a tempting offer Mr Potter" She rested her chin on her hand and fluttered her eyelashes shamelessly,"... but if I asked very nicely, do you think that we could defer those unspeakable things you're clearly thinking of, until after dessert."

Harry took her hand over the table. "Well, since you do ask so nicely. I suppose I could attempt to restrain myself;" he smiled and shook his head. "Who knew that the Black Widow had a sweet tooth."

In the end they shared a generous portion of tiramisu, trading bites back and forth until there was just a smear of cream and some strawberry crowns left on the plate. Harry leaned forward, brushing a little cocoa from Natasha's lip, loving the way she leaned into his touch.

The waiter came forward to take their plate. "Would you care for coffee?"

Harry raised his eyebrow at Natasha, who shook her head slowly.

"Time to go home?"

"Time to go home..."