Author's note:

My thanks to J.K. Rowling for allowing fanfiction writers such as myself to play in her back garden.

My writing is all the better for knowing Spikesbitch, Redskyatnight and Hexgirl, who have made a wonderful beta-reading team.

I love to receive reviews from readers, first or second time around. Please leave me your thoughts and feelings along the way.

The Unconditional Vow

Chapter One

Grimmauld Place

"It's quiet now

And what it brings

Is everything…"

'Leaving New York', REM

A crack sounded in the cool night air as Snape Apparated outside number 12, Grimmauld Place.

Although his hooded and cloaked figure was virtually indistinguishable in the dark street, he quickly concealed himself with a Disillusionment Charm before proceeding across the road towards the steps of the crumbling Georgian terrace.

He glanced upwards, trying to discern signs of life in the windows, but the house was bathed in darkness. The only light came from the stars shining directly overhead.

Cassiopeia twinkled brightly in the moonless sky, watching Snape as he hesitated at the front door of the Order of the Phoenix Headquarters.

In the hour that had passed since Dumbledore's death and Snape's subsequent escape from Hogwarts, pursued by Potter, Snape had barely had time to process the shocking events of the evening.

He had escorted Draco Malfoy back to Malfoy Manor to meet with the Dark Lord. After some careful manoeuvring, Snape had ensured Draco had not incurred the wrath of the Dark Lord for his failure to finish Dumbledore when he had been at Draco's mercy. Instead, Draco had been commended for his success, smuggling Death Eaters into the heart of Hogwarts right under the watchful gaze of the Headmaster.

However, Draco's hesitation at the Astronomy Tower had not gone unnoticed. Snape suspected that the Malfoy family's reputation was still very much in question and the Dark Lord would continue to punish them accordingly.

Snape himself had been awarded with praise for his actions, causing resentment amongst the other Death Eaters who could have killed Dumbledore in the moments before Snape arrived at the tower. Snape knew he was considered to be the Dark Lord's favourite, but this gave him no satisfaction whatsoever and left a bitter aftertaste in his mouth.

Now, standing outside number 12, Grimmauld Place, he was acting on the orders of his other Master. The one he had just killed.

Coldly detached from his emotions, Snape entered the Black family home and cast the Homenum Revelio charm. There was no one home. Snape knew the house-elf was at Hogwarts, so he was completely alone in the house. He lifted the Disillusionment Charm.

Snape stood in the dark hallway for a moment, unsure of what to expect or where to begin.

"Lumos."

The candelabra in the hall flickered into life, casting an eerie glow on the dark and dusty walls.

As his eyes adapted to the light, Snape became aware of the injury sustained to his right shoulder. Buckbeak the Hippogriff had attacked him during his duel with Potter, thereby forcing his retreat. Snape ignored the twinge of pain; the shoulder would wait. There was work to be done.

Snape strode down the hall, past the troll's leg umbrella stand, which he remembered Tonks tripping over the last time he was there. He sneered slightly at the memory until he was struck by the realisation that this would be his final visit to Headquarters.

He knew it would be unsafe for him to return; Alastor Moody would no doubt arrive in a matter of hours to secure the place.

Now, in the eyes of the Order of the Phoenix, Snape was a traitor and a murderer. He knew, as far as the larger plan was concerned, that this perception was essential. It was imperative that Snape retained his influence with the Dark Lord in order for him to be in a position to fulfil his promise to Dumbledore and protect the students of Hogwarts.

Snape forced himself to care little for this gargantuan misconception, knowing he only truly cared for what one person thought. And she was already dead.

With grim determination, Snape opened the door to the kitchen. As this was usually the hub of all activity it seemed a good place to start. He was met by a dusty table, surfaces completely cleared, pots and pans hanging in their racks. There was nothing out of place.

Snape climbed the stairs to the first floor, past the heads of generations of house-elves. Upon entering the drawing room he found the same thing; everything was neat and tidy and covered in a thick layer of dust. Cobwebs draped the shadowy ceiling and chandelier.

Frustrated and impatient, Snape held up his wand and muttered, "Accio instructions." Nothing happened. Stowing away his wand, his brow furrowed as he contemplated the implications.

Dumbledore had assured him that he had seen to the arrangements after his death; Snape would be safe from the prying eyes of the Ministry of Magic and suitably well informed of the Order of the Phoenix's next moves.

He had not, however, explained the details. Dumbledore had merely told Snape to present himself at Grimmauld Place, where he would find further instruction.

Snape ascended the stairs to the second floor with growing anxiety. He was accustomed to being on his own, indeed he preferred it that way, especially in the years that followed Lily's death.

But here, now, in the aftermath of the death of a man he had come to view as his mentor, the thought of being completely alone and disassociated from the Order filled him with dread. How could he protect Lily's son now?

At the top of the stairs he peered through the open door of Regulus Black's old bedroom. The green and silver wall hangings of the house of Slytherin called out to him, soothing his distress and calming his fears.

Pushing the door aside, he entered the room of the former Death Eater and glanced around for a clue; some suggestion of where to begin his search.

Amongst the framed photographs on the mantelpiece he saw a young Regulus Black, flanked either side by Horace Slughorn and Albus Dumbledore. The Headmaster's blue eyes shone brightly as he handed Regulus a trophy and shook his hand.

Snape felt his stomach lurch as he watched the small figure of Dumbledore performing his Headmaster duties in a looped playback, repeating over and over. The last time Snape had seen Dumbledore he was pleading to him.

Anger surged unrestrained through his veins as he relived the final moments on the Astronomy Tower, seeing the light fading from those piercing blue eyes.

Snape threw the picture across the room and began to tear open drawers and rifle through their contents mercilessly. Clothing and possessions were scattered across the floor as Snape searched in vain, his rage burning like a firecracker bouncing around an empty room.

When the last drawer had been opened and no stone left unturned, Snape swept out of the room and stormed into Sirius's old bedroom.

His anger flared at the ostentatious Gryffindor decorations adorning the walls. The red and gold insignia mocked him as he was reminded of Lily's house and all that it entailed, along with his more recent understanding of the choice he could have exercised in his own Sorting.

Snarling at the Gryffindor banners, he realised such an overt display in a house of pureblood Slytherins was a powerful statement. Snape felt awe at the sheer audacity, and also a sense of shame.

Things might have worked out differently with Lily, had he not been so eager to join Slytherin and pursue the Dark Arts. He regretted some of the choices he had made in the past, wishing he had known what the cost of those moments would be. Life could have been so very different.

Snape grabbed the red and gold hangings and attempted to tear them from the walls, his grief and loss ripping him in two. But the banners would not budge; a well executed Permanent Sticking Charm had seen to that.

He growled at the walls, unable to vent his frustration. A photograph of grinning Marauders taunted him as he tore aside furnishings and broke open drawers. He searched; searched for anything. Searched for something to anchor him in this storm.

Then suddenly it was there in his hands - an old parchment envelope addressed to Sirius Black, written in Lily's handwriting. His heart skipped a beat as his trembling fingers opened the letter and his eyes devoured the contents.

A photograph of an infant on a broomstick fell from inside the letter. Snape knelt down and retrieved it from the floor. With a rush of emotion he saw Lily's smiling, laughing face. She looked just how he had always tried to remember her.

Tears ran down his hooked nose onto his torn robes as he sobbed, overcome with guilt and shame, clutching to this one connection to Lily and his very reason for existing.

He knelt there on the floor for what could have been an eternity, awash with previously repressed emotions. Grief for Lily was now mixed with his new grief for Dumbledore and it rendered him incapacitated, unable and unwilling to move.

His hands shook and his heart pounded as his damaged soul comprehended the magnitude of his burden. Snape had killed Dumbledore. He was also to blame for Lily's death. How would he find absolution now?

The answer came to him like a shower of ice cold water; he must compose himself and keep looking.

Slowly he started to regain a measure of self control, the sobs subsided and tears ran in silent tracks down his face. Snape looked again at the letter and the photograph, assessed the first page as worthless and discarded it. He tucked the second page into his robes; he could imagine the letter had been written to him that way.

Snape ripped the photograph in two and tossed the half containing the Potter boy across the room. It landed out of sight, underneath a chest of drawers.

Placing the picture of Lily laughing carefully inside his robes, he grasped the bedpost in support and made to rise from the floor.

A sudden flash of light halted his progress, as he instinctively turned, wand at the ready, shielding his eyes from the flash of amber flame roaring across the bedstead.

The fire disappeared as quickly as it had arrived.

In its place, sat at the foot of the bed, was Dumbledore's phoenix, Fawkes.

The bird peered forlornly at Snape, as if in interminable pain. Fawkes looked old and weary, his feathers starting to fray. The phoenix's sorrowful eyes took in Snape's battered visage and bleary red eyes.

Snape was flooded with understanding; Dumbledore had sent Fawkes to him upon his death. This was the instruction he had been searching for, his link back to reality and life. Relief swam through him and as the adrenaline diminished he let out a reflexive sigh.

He rose from the floor, wincing in pain as he became aware of the extent of damage to his shoulder. Through his torn robes he could see a deep wound and his shirt was soaked with blood. Clutching at his injured shoulder he sat down on the bed next to the phoenix.

The bird considered him for a while as they sat side by side. Snape had never seen Fawkes so sad and subdued. The phoenix's beady eyes seemed to be appraising him warily.

When their eyes made contact Snape blanched and crumpled. Holding his head in his hands, pulling his black hair away from his face, Snape began the process of rebuilding his internal defences, ready to face what was still to come on this dark and seemingly endless night.

The phoenix's red and gold plumage sparkled in the candlelight as it approached Snape slowly, a single glistening tear forming like a crystal bead in its eye. Leaning in towards Snape, the phoenix's tear dropped onto the wounded shoulder. With a rush of warmth the skin healed and the pain evaporated.

Despite himself, Snape felt a rush of gratitude towards Fawkes for this act of kindness and he nodded his thanks to the bird, whose head dipped in acceptance. Something passed between them in that moment. A new understanding; a deeper contact forged by shared grief.

Snape and Fawkes sat in silence for a few more moments. Snape felt a familiar numbness wrap itself around him like a cloak as he gathered himself, in preparation for the imminent departure from Grimmauld Place.

As he stood up, the phoenix opened its wings and with a couple of elegant beats Fawkes was airborne. Hovering above Snape, the phoenix extended its feet towards him, and Snape reached up to catch them.

In a flash of flame, the pair vanished.