Disclaimer: All characters and universe are the property of JK Rowling, this fanfiction is purely for entertainment purposes and I receive no profit from it.

Author's Note and Warnings : This fan fiction is Cannon up to the moment of Dumbledore's death. I am rating it M for possible slash in later chapters as well as dark themes. I look forward to exploring the dark side of magic and hope you all enjoy the ride.

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Harry splashed water on his face, feeling extremely ill to his stomach. Dumbledore was dead and he'd been forced to watch it happen. Draco hadn't hesitated, just aimed and uttered the curse. He had seen Snape's face in the dark, the pain that flashed across it and then the shock as Bellatrix had turned her wand on the Professor. He had thrown the invisibility cloak aside, feeling the Petrificus curse release him and gone to Snape's aide.

The man in question was sitting on the end of a bed in hospital wing, talking in hushed tones to Minerva. Harry, for his part, felt almost numb. Tonight had been for nothing, the bloody horcrux hadn't even been there. He felt the rage bubble up in his chest and slammed his fist into the glass, feeling it shatter and slice into his flesh. He heard footsteps but he didn't pay any heed, his magic swirling dangerously through the room. It wasn't fair! All of this had been for nothing. NOTHING!

Severus felt it and his head lifted instantly. "Minerva, get Poppy and wait outside." He said and moved towards the teen that was caught in a swirl of wild magic. He took a deep breath and approached, casting a shielding charm around himself, just in case. He put his hands on the boy's shoulders. "Harry." He said forcefully, trying to get his attention and forestall the explosion he could feel building.

"WHY?" Harry choked out, tears starting to fall. The magic exploded outwards, shattering windows and throwing things aside and then it was simply gone as the boy collapsed into a fit of wracking sobs.

Severus dropped his shielding charm and just stayed there, an anchor for the boy. He had no idea how long the teen sobbed into the sink, but when he finally settled down Severus gently steered the young man to sit down. "Let me see your hand." He said softly and took it carefully removing a large piece of glass from one of the cuts. He then used a spell to remove the rest and applied a salve and wrapped the hand. "There was nothing you could have done tonight to save him." Severus said softly.

"But it was all for nothing..." He whispered. "How could he die?"

"The minute he drank that potion Harry, his fate was sealed. Even with my help, he would not have survived the night." Severus said gently. He had created that poison for the Dark Lord; he knew all too well the effects of it. "He knew he was going to die tonight, it was just never supposed to be Draco who cast the curse." He rubbed the bridge of his nose. "He's been fading all year, since he attempted to destroy the Gaunt family ring in the summer. He wanted to teach you what he could before he passed."

"How can I find the other horcruxes? I don't even know where to start." He felt utterly hopeless. It was even worse than in his third year when he'd been plagued by Dementors, he felt cold right through his very soul.

"I will help you Mr. Potter. You have my word." The potions master said without thinking too hard on it. If Bellatrix had tried to kill him, the order would have needed to come from the Dark Lord himself. The proverbial line had been drawn in the sand. His old mentor had finally decided to cut the last tie between them. His little dance between the two greatest wizards of the age was at an end, finally.

Harry nodded, meeting the Potion Master's dark eyes. "If I'm here, I'll be putting everyone in the castle at risk. With the headmaster dead, Voldemort will come after me." He knew it, with frightening certainty. People would die if he stayed here.

"Yes, he will." Severus stood. "Go to your friends in Gryffindor Tower; make sure they are all in one piece after tonight's events. Then, once they are all asleep, use that map of yours to find my chambers. There are things we must discuss, and plans we must make." The Potions Master felt older than his years, weary. The safety of Lily's son was now his only calling, and to save him he would need to teach him to fight fire with fire.

"Yes Sir." He said quietly. "I know we don't get on Sir, but he trusted you...the least I can do is extend that same trust." He offered him a hand, looking older than his sixteen years would have suggested.

Severus reached over and took that hand, gripping it firmly. "Be careful in offering trust Mr. Potter, there are few in this world truly worthy of it." He then let go and swept out of the Hospital Wing. Minerva and Poppy went in to check on Harry and he continued down to the dungeons.

Once in his quarters he poured himself a very large glass of fire-whiskey and downed it in a single go. He then poured another and collapsed into his chair. He knew it would take hours for Potter to get his friends settled after all that had transpired this evening. He had some time to try and talk himself out of this madness. He simply had to be out of his mind to even be considering taking Lily Potter's son down this path. Dumbledore had forbidden him to teach the boy, claiming that the Dark Arts would taint the child and damage him beyond repair. 'Because raising him like a lamb for slaughter was really in his best bloody interests.' He thought uncharitably. He knew all too well what learning the Dark Arts entailed, he'd delved deep into those depths...far deeper than even Albus had known. Oh yes, if Albus had truly known he would never have allowed him so close to his precious students.

His mentor had seen his natural predisposition and had taken him into his power, forging and tempering him like a well-honed blade. He'd felt that same raw power tonight in Potter, he could still feel it ringing against his own. All young witches and wizards could display moments of raw magic, though it usually quieted down as they approached adulthood, but there was a feel to Harry's power that was achingly familiar to him. It was a power that begged to be directed and challenged. He hastily swallowed back the rest of his glass and set it down beside him. If he was really going to do this, take Potter as his student in *this*, he would do it properly. Elements save them both, but he would.

He got up and went to his bedroom and took a small plain wooden chest out of his wardrobe. He cast several disarming spells before he opened it and removed the contents it had been protecting. He carried them out to his sitting room and cleared his coffee table with a muttered charm. On its now barren surface he laid a silver bowl, a dagger, an amulet on a heavy silver chain, and lastly a quill and parchment. The potions master then settled in to wait. Potter would come, of that he had absolutely no doubt.

Hours passed before there was a knock at his door. Severus flicked his wand and the door swung open to allow the young wizard entrance. He sat up in his chair and blinked the sleepiness from his eyes. "I trust all of your friends are all right?" He asked, watching the Potter boy closely. He was trying hard to judge him without the ghost of James floating in front of him. He would need to be objective if they were both to survive this.

"Yes, I shared my liquid luck with them tonight." Harry said and shut the door behind him as he walked deeper into the room. It was nothing like Snape's personal lab that he'd spent his disastrous Occlumency lessons in. His professor was sitting in an overstuffed chair by the fire, opposite a matching chair that was empty. There was a coffee table between the chairs and Harry's eyes went over the contents curiously.

Severus found himself nodding approvingly. "It may well have saved their lives tonight, five points to Gryffindor for good judgement." He found himself awarding the points without feeling too badly about it. "Sit Potter, would you like a drink? Given the night you've had, I think we can bend some school rules." He stood and poured the teenager a small measure of the fire-whiskey. "Sip, don't gulp." He warned and sat back down.

Harry seemed in shock that Snape had awarded him points, and was being civil. "Uh...thank you, Sir." He managed to say and took a sip of the liquid, blinking as it burned the back of his throat. He couldn't help but cough and he felt his eyes water a bit.

Severus's eyes glittered a bit, amused to watch the teen take his first real drink. He'd been far younger than that when he'd started raiding his father's scotch. "All right there Potter?" He asked, not hiding his amusement. It was nearly four in the morning; he blamed his lack of control on that.

"Yes sir, just a bit...strong." He said and cleared his throat. "You said we needed to discuss some things Sir?" He asked, the dark shadows gathering under his eyes betrayed just how exhausted the boy was.

"Yes. My question to you is how far are you willing to go to defeat the Dark Lord." Severus said, dark eyes piercing into Harry's. He didn't mince words, this was too important for there to be any doubt about what he was asking.

Harry sensed there was a lot unsaid in that statement, but he also knew it was a test. He sipped the whiskey again; it didn't burn so much this time. "As far as it takes. He murdered my parents and for that alone I'd do anything to kill him." The bitterness in his tone dripped like poison as he spoke. "What did you have in mind?"

Severus nodded. "To fight the Dark Lord, you need to learn what he'll use against you. I'm offering to teach you everything I know, without any limits. If you wish to be my student, I would be honored to be your mentor in this." The words were important.

Harry found himself considering it. "One question first, why now? Why didn't you offer to teach me these things before?" He needed to know.

"I was forbidden to." He said. "The headmaster felt there were things that you shouldn't learn. He had his own plans for you but all I will say is that my only goal is to get you through this alive. I once promised someone that I would protect you, and the best protection I can give you is the knowledge I have." Severus said. "Regardless of your answer I will help you hunt down and destroy the Horcruxes." He made sure that he understood that.

Harry nodded and looked into the fireplace for a long while and then nodded. "I would be honored to be your student." He looked at his Professor.

"Then come here and kneel in front of the coffee table." He said and moved to kneel as well. He reached over and took Harry's hand as soon as he knelt. "In the old days, before most students attended magical schools, the bond between Mentor and Student was considered the most important bond outside of family." He told him as he took the dagger in his other hand. "Even today there are some kinds of magic that can be taught only in this manner. I'm going to cut your palm and then my own. Our blood will be used to seal a magical contract between us, as well as allow me to find you if you are in great peril, or to summon you to me if I need you." Severus could feel the teen's hand tremble a bit as he put pressure on the dagger.

Harry hissed a bit as his skin gave and blood welled up in the wound. He let Snape turn his palm over the silver bowl and after several drops fell he watched as Severus bound his hand in white silk. Harry suddenly found himself in possession of the dagger. Severus offered him his hand and with a few deep breaths he managed to make the cut into his teacher's palm. He copied Snape's earlier motions and added his blood to the silver bowl and then wrapped it in white silk.

Severus smiled encouragingly. He dipped the quill into their mingled blood and wrote his name elegantly on the page and the offered the quill to Harry. Mentally he cringed; the boy's penmanship was simply atrocious. They would be fixing that at some point. He then folded the paper and laid the amulet on top. He took his wand and tapped it twice. "Sanguinis Contractus." He said and the parchment dissolved into a brilliant white light and disappeared into the amulet. Severus took the amulet and placed it over Harry's head, settled it on his chest just over his heart. "Tiro Eligitur." He said the amulet disappeared, white light sinking into Harry's chest.

Harry fell forward, gasping for air. The light hot and felt like it was searing into him. Then suddenly it was gone. "What?" He managed to say, feeling very drained.

"That completed the bond; it takes a lot out of us both." Severus looked quite tired as well. He waved his wand and the items floated out of the sitting room and back into their chest in his bedroom. "Come Mr. Potter, I think we are both in need of some sleep." He stood and offered the young wizard a hand. "You can use the spare bedroom tonight as I don't think you'd make it all the way back to the tower." He was past caring if it seemed inappropriate. Tonight propriety could go fuck itself for all he cared. He'd just completed a very dark ritual in the middle of Hogwarts, having a student spent the night in his quarters seemed rather insignificant in comparison.

"Thank you Sir." Harry said and stood up but had to lean into Snape for support. His legs felt like they were made of rubber. Together they walked down the little hall to the left.

"Bathroom is just there, and this is the guest room. Goodnight Mr. Potter." He said and helped the boy to the bed and then withdrew. "There is a vial of dreamless sleep in the bottom drawer there, I suggest you use it." He added before shutting the door.

Harry sat there a moment before he opened the bottom drawer and found the vial where it lay tucked neatly behind a book. He opened and sniffed it, remembering the smell from the other times he had taken the potion. He drank it back and then slipped out of his cloth and crawled under the blankets, too tired to worry about pajamas. He spelled off the lights and was out cold as soon as his head hit the pillow.

In his room across the hall Severus was also contemplating a vial of dreamless sleep. He hadn't touched the stuff in more than twelve years, having gone through a period of addiction after the death of Lily. 'I'm sorry Lily; there really is no other way. I promise to keep him safe and I will not fail him, like I failed you.' He thought desperately as he took the potion and curled into his bed.

TBC