Plot, new characters, new magical terms and abilities etc. are my intellectual property. If you want to borrow then please kindly ask. JK Rowling's characters and Wizarding Universe are all uniquely hers. I don't make any money from this.

ALTERNATE UNIVERSE

Summary:

Snape learns a lot about real love, acceptance and support in the aftermath of Dumbledore's death - and the Wizard he sacrificed so much for. Inspired by "The Unconditional Vow" by Agnus Castus. SS/OC Aspberger's Syndrome

Author's Notes: Inspired by "The Unconditional Vow" by Agnus Castus on Hex. Do read that amazing story!

Chapter note: The conditions of the vow are taken from Chapter 4 of "The Unconditional Vow"

Chapter 001: The Unconditional Vow

Nerysarwen Pendragon had barely set foot in her front door when red and gold flames shot up in her fireplace. She was tired, dead tired, and in no mood to be dealing with anyone. She cursed herself for not shutting down the talking fire as she should have after a friend had dropped in just as she was setting off to work earlier. There was always a price to be paid for being in a rush.

'Nerys... please...' a familiar voice pleaded as she took off her coat and slung it over a chair. 'It's important!'

It certainly had to be for the likes of Albus Dumbledore, Headmaster of Hogwarts School of Witchcraft & Wizardry, to come calling. By the looks of the message beacon he had been trying in earnest for some time.

'I am here, Albus,' she said nervously as she sat down on the old chest that functioned as her coffee table. 'I literally just got in from work.'

'I would not impose unless it was of the greatest importance. May I?'

'By all means,' Nerys said standing. 'Just give me a moment.'

A wave of her hand and the drapes on all the windows were closed and the shutters locked. One couldn't be too careful in these dangerous times, not even an Unspeakable working in the Ministry's Department of Mysteries.

OOO

Dumbledore sat quietly in Nerys's candlelit kitchen, his blackened right hand confined to his lap as he stirred his tea with his left.

'Your hand, Albus. What happened?'

'My curiosity and weakness.'

'You – weak? That doesn't sound like you at all.'

'I take it he hasn't had that conversation with you – yet.'

'He doesn't speak to me any more than he does you.'

'I am truly sorry. I had hoped that he would finally see sense where you are concerned.'

'I gave up hoping for the impossible long ago. So; what brings you here at this hour?'

'You once offered your assistance, but only in the direst of situations. The time has come where I am in desperate need of your talents. You are uniquely placed for the demands of this most peculiar task.'

'What is that you require of me?'

'I need you to provide sanctuary for a member of the Order of the Phoenix.'

'When?'

'Hazarding a guess – in a year's time at the most. But less than that perhaps. I am not entirely sure but thought it best not to delay; you will need to prepare.'

'Prepare for something that hasn't even happened? Something that might not ever happen? That does not make any sense.'

'In time it will. Trust me.'

'I've always trusted you, you know that,' Nerys said softly as she patted his good hand and gave him a little smile.

'My dear Nerys; I wish I had done so much more for you,' Dumbledore said sadly.

'Being able to go to Hogwarts was more than enough. I cannot thank you enough for that. Anyway – yes, I will do it.'

'I have something else to ask of you; it is very necessary for this mission.'

'Oh? What?'

'A vow. I must insist that you make one.'

The smile was wiped from the young woman's face as she looked at the Greatest Wizard of the Age in astonishment tinged with disappointment.

'You don't trust me,' she said angrily. 'Me – of all people after all this time and everything we have been through together?!'

'I do trust you! But I also know that you have your limits, Nerys! I would have to make the same demand of anyone else! We all have our weaknesses, including you! It would be a grave mistake on my part to not account for that!'

'A vow...just to have a housemate for a while?'

'A housemate who may very well be on the run from the authorities and in the most difficult of circumstances, my dear.'

'Hmmph – a certain someone would definitely loose his rag if he had any idea...not because he actually cares about me, mind you.'

'That he would and unfortunately no he doesn't; not as he ought to at any rate.'

'Alright then, I will swear to it.'

'You do understand...'

'...that there are consequences should I fail to live up to the terms? Aren't there always?'

The Headmaster took out his wand with his good hand as he clasped Nerys's arm with his damaged one. He held his wand over their arms and began the incantations.

'Nerysarwen Pendragon: Do you consent to making a vow of your own free will?'

'I do.'

A double band of red shot and gold shot from Dumbledore's wand and wrapped itself around their connected arms and pulsated before being absorbed. The same happened again with bands of royal blue and silver as Nerys held her free hand aloft over their joined arms, signalling her formal commitment to the spell.

'Do you promise to provide a safe haven for a member of The Order of the Phoenix at moment of great need and possible peril?'

'I do.'

A double band of red shot and gold shot from Dumbledore's wand and wrapped itself around their connected arms and pulsated before being absorbed.

'Do you promise to do all that you can to ensure they stay alive and fulfil their purpose?'

I do.'

A double band of red and gold shot from Dumbledore's wand and wrapped itself around their connected arms and pulsated before being absorbed.

'Do you promise to absolutely trust this person, despite their actions and no matter how disloyal they might appear?'

I do.'

A double band of gold and silver shot from Dumbledore's wand and wrapped itself around their connected arms and pulsated before being absorbed.

'And, finally, do you promise to accept this person completely without any conditions?'

'I do.'

A double band of gold and silver shot from Dumbledore's wand and wrapped itself around their connected arms and pulsated before being absorbed.

'It is done,' Dumbledore said quietly as the newest member of his latest incarnation of the Order of the Phoenix held up her tingling arm and hand and flexed her fingers.

XxxOOOxxX

Over the next few months Nerys busied herself with preparing for her unknown house guest. She'd never been one for the hubbub of city life and had made her home in Brecon Beacons in Wales, the ancestral home of her late mother's family. Her duplex farmhouse was located near the top of one of the many steep hills near the Black Mountain in the Parish of Myddfai. Working for the Ministry in London was one thing, but she wouldn't trade the tranquillity and panoramic views over the forests and wooded valleys of her beloved Cymru for all the gold in Gringotts.

It was only when she was in the midst of arranging the furnishings in the new guest bedroom that Nerys realised she had no idea who she was risking so much for.

XxxOOOxxX

Nearly a year later Dumbledore sat in his office at Hogwarts brooding over his latest sojourn outside of its hallowed halls. What would Nerys have thought when he saw her late last summer if he'd told her the truth about his withered, black hand; that it was had been the beginning of a slow, torturous death and no thanks to his greatest weakness – the love of power.

The previous Summer he'd started the hunt for the dark objects whose destruction was necessary to bringing down the metaphysical terrorist of the Wizarding World, the Dark Wizard Lord Voldemort. In a quest for immortality and untold power the Dark Lord once known as Tom Riddle had undertaken one of the most destructive forms of Dark Magic a wizard or witch could inflict upon themselves. He'd split his soul into fragments and concealed each in an object. Knowing the Dark Lord as well as he did, the Headmaster realised that these Horcruxes would not be ordinary items and Voldemort had undoubtedly cursed them as a protective measure in the unlikely event that someone discovered his secret.

Dumbledore had located one them, a ring that had been in Tom Riddle's family for generations. He recognised the stone in the setting as being the Resurrection Stone, one of the assumed mythical three Deathly Hallows which gave the possessor power over Death. The Headmaster, was already in possession of another of them, the Elder Wand – the most powerful wand that had ever existed.

He;d wanted the Resurrection Stone for years because it would allow him bring certain family members back from the dead so that he could atone for past mistakes and a most grievous selfishness that had lead to the death of his beloved sister. So blinded by the power inherent in the stone was he that the Headmaster quite forgot himself and put the ring on his right hand. The moment the ring made contact with his finger in this way, the curse activated and nearly killed him. His undeniable skills saved his life so that he could return to Hogwarts and consult with Severus Snape, the school's Potions Master and Head of one of its four Houses. Snape was quite prodigious himself – and the only one to whom the Headmaster would entrust further treatment. Snape had done what he could but estimated that at best the Headmaster would live a year, if he was lucky.

The Potions Master was also integral to the resistance activities of the Order: he was one of Voldemort's Death Eaters and he'd turned spy at great personal risk at the height of the First War of Voldemort. The Dark Lord had seemingly been vanquished one fateful Halloween Eve in a confrontation that also claimed the lives of Lily Evans and James Potter, the parents of The Boy Who Lived. Harry Potter was but a year old when Voldemort attempted to kill him with the Killing Curse and it rebounded. Voldemort seeming vanished into nothingness while baby Harry survived albeit with a scar in the shape of a lightening bolt.

Though many throughout the Wizarding World celebrated, Dumbledore knew that the Dark Lord would return from wherever it was that his desecrated spirit had to be lingering. Snape and Dumbledore had had their work cut out for them ever since the boy arrived at the school to begin his customary seven years of study. He-Who-Must-Not-Be-Named finally returned in a corporeal form in Potter's Fourth Year and it had one thing after another ever since.

But time was running out and despite the mistakes he'd made along the way the Headmaster was now making sure that Harry knew as much Dumbledore thought he needed to know to be able to vanquish Lord Voldemort once-and-for-all in their inevitable final confrontation. He'd enlisted Potter's aid in gathering and destroying the remaining Horcruxes. They'd taken the journey together away from Hogwarts and in doing so, it seemed he'd hastened his slow death.

The last object, a locket belonging to one of the school's four founders, could only be taken by drinking a toxic Dark Potion. The curse of the ring which had been temporarily contained was already spreading rapidly. His death would be publicly humiliating and excruciatingly painful. His greatest weakness would be laid bare for all to see.

He could not bear it and he would not.

The Greatest Wizard of the Age had always been a man with a plan and his eventual death would be no different.

XxxOOOxxX

It had been but an hour or so since Dumbledore died and he'd been forced to flee Hogwarts with one of his students, Draco Malfoy in tow and Harry Potter in hot pursuit. Severus Snape, formerly Potions Master and Head of Slytherin House, took little notice of his throbbing injured shoulder and bloody clothes. What he needed more than anything was the help that the Headmaster had insisted would be there for him in what would be one of the defining moments of his miserable life.

In the immediate aftermath, Snape's first priority was to ensure that Draco was not blamed for failing to kill the Headmaster. He had taken his Death Eater Godson to the Malfoy family stately home which also served as the Dark Lord's headquarters. Voldemort had given Draco the task to kill Dumbledore as a punishment for Draco's father's failure at the Battle of the Department of Mysteries the year before. Draco's pitiful attempts throughout the school year had nearly resulted in the deaths of other people, but not the intended target. The final confrontation with Dumbledore was equally pathetic. The boy managed to disarm the old wizard but couldn't bring himself to do the final deed.

In the end someone else had to step into the breech. As with just about everything else, this too had been anticipated by Dumbledore, with the Potions Master duly informed. Both had been confident that the Dark Lord had really meant for Snape to do it in the end as the ultimate test of loyalty and no thanks to the Chinese whispers against him on the part of Bellatrix Lestrage, a fellow Death Eater and Draco's aunt on his mother's side.

So it was that Severus Snape found himself standing before the Dark Lord and a select few of his inner circle. His was a decidedly inspired accounting as it ensured that Draco was looked upon favourably for his success in getting Death Eaters into the castle, a task that had been nowhere near easy in and of itself. Draco had also distracted the Headmaster, Snape said, an inspired act which allowed Snape to finish the Headmaster off with the Killing Curse.

The Potions Master's quip about how he had to give credit where it was due and award ten points to Gryffindor for Dumblefore's perfect back-flip off the top of the Astronomy Tower was the icing on the cake.

The Dark Lord laughed uproariously.

'The look on his face when you aimed your wand! Just marvelous! Dumbledore always was a bit of a fool,' Voldemort commented with a maniacal grin in his high cold voice. 'You have done well Severus – exceeded my expectations, in fact. The Ministry will be leaving no stone unturned to find you. Lay low. I will summon you when I have decided how best to proceed with taking control of Hogwarts. It will take some time; my first priority is securing allegiance of the Dementors and the release of old comrades from Azkaban before overseeing to the fall of the Ministry personally. You are too valuable to be wasted on such mundane operations.'

'Thank you My Lord,' Snape said evenly as he bowed low. He forced himself to walk calmly from the room and not look back.

It seemed the Dark Lord was quite displeased by someone else's performance that evening and they would be punished for it. Snape had been punished enough himself in the past to know that whoever it was was in for a very long night of hell.

He'd endured enough already.

Now he just wanted dreamless sleep.

XxxOOOxxX

Dumbledore had charmed an old "Dumbledore's Army" coin, remnant of the student resistance from the year before when the Ministry had taken control of Hogwarts, to be used as an illegal portkey. As soon as Snape had left Malfoy Manor in Wiltshire he'd Disapparated to Tintagel in Cornwall where he found and activated the coin as instructed.

The Potions Master found himself standing in a thicket of trees in an old gothic graveyard in the village of Godric's Hallow looking around in disbelief. The old man always did have a rather perverse sense of humour but there was nothing to be laughed about in his choice of rendezvous point. Whatever the rationale behind this was, it was lost on him at the moment.

His fathomless black eyes scanned the nearest rows of graves before resting on one in particular.

'Pull yourself together!' he admonished himself. He had gone through too much in the past few hours to loose control of his faculties at this last hurdle. He willed whomever it was that he was waiting for to hurry up so that the spectres of his past could be left in peace.

After what felt like hours, a very large familiar bird with bright red and gold plumage swooped through the graveyard and hovered in front of him just above his head. It was Dumbledore's Phoenix.

'Fawkes? What the devil...?'

The bird let out a low mournful cry as a single tear dropped onto Snape's shoulder.

'I see,' he commented before reaching up and clapping his hands around the creature's legs, careful to avoid its sharp talons.

There was a flash as both disappeared, and thus began the first part of his journey into uncharted territory.