Title: Viper

Disclaimer: J. K. Rowling and associates own these characters. I am writing this story for fun and not profit.

Rating: R (for violence, not sex)

Pairing: Harry/Draco (eventually), past Harry/Ginny

Warnings: Creature!fic,(vampire Draco), angst, violence, profanity, OC character deaths, dark Harry. DH spoilers, but ignores epilogue.

Summary: Sequel to 'Mongoose.' Draco is more convinced than ever that Harry's blood and magic are perfect for him, and, as a developing master vampire, he'll have the power soon to enforce his will. But Harry has other problems—namely, a series of mysterious murders and thefts that he suspects vampires are at the bottom of. If there are any vampires capable of resisting their instincts, that is. And if there are, then the wizarding population of Britain's in more trouble than they can imagine.

Author's Notes: This is a dark story. It does not feature a nice Draco. It does not feature a nice Harry. Also, you should really read 'Mongoose' to understand why Harry and Draco are the way they are. With those warnings, on with the show.

Viper

Draco hung upside-down from the ceiling of what had been his home when he was mortal, his fingers driven into minor cracks in the stone and his mouth shut to keep the light from gleaming on his fangs. He had hooked his legs around a rafter and chosen a corner shadowy even as this time of day, the early dusk, to keep his hair from shining.

It worked perfectly. The humans below hadn't detected him with their spells; those spells focused on such traits of mortals as moving blood and possession of wands. And of course they assumed that no one could possibly be clinging to the ceiling above them. The ceiling was mostly smooth stone.

Draco hissed without opening his mouth as he listened to them. Only the thought of what they would say if they knew a nightmare hung above their heads kept him from attacking immediately.

"And you're sure there'll be no complication from the previous owners?"

"The Malfoys? No." The second human, a man with dark hair that clung to his head as if oiled, had a barking laugh. Draco told himself he would remember it. "Lucius Malfoy is in prison, and never getting out of it. The son disappeared years ago. And they found the old woman dead. Murdered. Throat torn out, like she'd met some wild animal."

Draco stirred, but soundlessly.

"Really?" The first man, a heavyset bloke with red hair that brought back a number of Draco's mortal memories, sounded fascinated. "Did they ever figure out what killed her?"

"Who knows?" The indifference in Oil-Hair's voice was perhaps the greatest insult. "A werewolf that made it through the wards, or something like. I know the wards weren't as strong without her husband's presence here."

"Then is the house safe?" The red-haired man stared around apprehensively, as if he might surprise a werewolf hiding in a shadowed corner. He didn't look up, of course. Draco had noticed that humans rarely did.

"Oh, completely." Oil-Hair smiled at him, and if the red-haired man believed that smile was sincere, he was a greater fool than Voldemort. "It's been extensively re-warded, and it's ready to become the home of a new bloodline."

No, it's not, Draco thought.

"All right." The red-haired man reached out to accept the key from Oil-Hair.

They couldn't have timed it better if they had been trying to attend to Draco's special needs. The sun had moved far enough from the window that the light wouldn't burn Draco as he descended, and sunk far enough below the earth that power surged through him.

He unhooked his fingers from the ceiling and fell. Vampire muscles did what their owner told them to, so his legs coiled easily, supporting his weight, and his much tougher bones refused to break. He moved towards the men, the motion attracting their attention where the slight thump of his landing hadn't.

"I thought you said the house was empty," the red-haired man muttered. He backed away a step, and then hesitated, as if he weren't quite certain whether Draco was a threat. Draco had met his eyes and begun to project his thrall.

"It is." Oil-Hair stepped forwards. Draco could feel his mind fighting like a fish hooked on a line. He was made of sterner stuff than the red-haired man. "No one is supposed to be here." His tongue stumbled over the words, but he managed a glare at Draco nonetheless.

Draco paused with one foot lifted from the floor. Perhaps the thrall can fail. He had never heard of such a thing, but then, as he had told Potter, Caspar had not told Draco or any of his nest everything about being vampires, for fear they would rebel against his control.

But when he "leaned" forwards and pushed the thrall towards the two humans like a man laying his shoulder to a heavy wheel, their expressions became soft and confused, and they stepped eagerly towards him, their own movements as smooth as his.

I'm stronger, now that I'm free, Draco thought as he opened his mouth and his fangs folded down to touch his bottom lip. I simply need to learn how to use it.

The men provided the blood he'd been craving, but it was like a diet of gruel and fruit compared to what Draco knew he could have. He stepped back from them when he was done feeding and flicked the thrall like a lash through their minds, ordering them to leave and Obliviate themselves. Both stood and stalked out the door, never looking back at him.

I could have Potter.

The memory of blood thick with adrenaline and alive with magic flowed through Draco, and his fangs promptly folded down from the roof of his mouth again, though he had just fed.

He is still my Long-Desired.

And now that I know what happened to my mother and no strangers are moving into my house for the present, I think I will find him again.

*

Harry opened his eyes and sat straight up in bed. He stared ahead of him for a few moments, concentrating desperately. The scattered tendrils of a dream trailed through his mind, and he wanted to hold them still. They contained an answer to a problem he'd been trying to solve.

And then he knew, and he leaped from bed, grabbed his lighted wand, and raced across the room towards the stack of files he'd brought home from the office last night. He shivered absently, which reminded him that he was naked, but that didn't bother him; he had stopped caring about being naked when Ginny died.

He tore into the files, finally locating one in a battered folder stained with Ron's coffee and then another in a garish purple folder that he wanted. He sat back and read through the papers again, looking for the phrase he remembered.

Yes, there it was. Both the dead victims had had similar wounds on their bodies, and the investigating Aurors had even used the exact same words to describe them.

Round and purple, with punctures in the middle.

Both had assumed that they were snakebites, but no snake venom had been found in the victims' bodies. Neither had any other poison, or Dark magic for that matter. Somehow, both victims had been slaughtered without putting up any magical resistance—although both were powerful wizards—and their valuable collections of portraits and silver statuettes made away with. The only evidence was these wounds, and how had they killed if they were so small and contained no poison?

But Harry knew. The problem had connected with his years-long obsession in his dream, which wasn't a surprise. He often dreamed about vampires, since he hunted them.

He Summoned a book from a nearby shelf and flipped through it feverishly until he revealed a sketch of two puncture wounds. He lit his wand and bent near it, nodding and smiling before he'd looked for a full minute. He'd known what he would find, and not only because of his obsession. He'd acquired a much better memory since Ginny died and he discovered that he'd need a good memory to take revenge on the creatures who killed her.

Yes. A vampire's punctures looked like a snakebite. Harry smiled and brushed his fingers over the page, glad that the book had vindicated him.

But, of course, someone would have reported if the bodies had been drained entirely of blood, and rogue vampires would have been suspected immediately. So something had been done to make the suspicion harder to verify.

Harry read the first file again, carefully. And there it was, a few sentences that he hadn't paid much attention to at first, because, well, not every crime was a vampire's fault, and he did sometimes try to ignore his obsession.

I noted a faint trace of a charm on the room, rather like a glamour. I cast a Finite, on the theory that perhaps the "stolen" goods were concealed in their original places with a powerful illusion, but this revealed nothing.

Harry leaned back against the bed, tapping his fingers restlessly on his knee. Glamour charms might have been used to hide stolen goods, but not in this case. He did think that the vampires had stolen the collections they had come for.

But other spells could leave glamour-like traces. They might not be used very often, given the magical strength needed to power them, but they existed.

Harry felt his face crack into a smile. It split his lip when that happened, and he rubbed absently at his mouth.

A Replacement Charm—such an innocent name—might leave a trace like a glamour. And Harry knew, from studies he had made in magic associated with wizarding vampires, that someone could use it to replace the blood in a drained body, provided enough blood was available in another source. A sufficiently skilled wizard or witch might even replace the sense of a vampire's presence with the victim's magical signature. It would take finesse, but vampires had no lack of power to hire finesse or time to find it. Harry knew that, none better.

He might be wrong. He might be allowing his general grief against vampires to lead him into seeing plots where there were none.

But, thinking of the description in the reports of the murders and the image in the books he'd consulted, Harry didn't think he was.

*

Potter lived in a small house on the moors. It was inconveniently far from any wizarding town, and had a lack of small dark places where Draco could have sheltered from the sun, so he had to approach it at night. And then he paused five miles away, because Potter had more anti-vampire precautions surrounding his house than he'd ever seen.

It was understandable, Draco admitted to himself, pacing back and forth and staring towards the house that held the wizard whose blood and magic tasted the best to him. Potter was a vampire hunter who specifically targeted nests. If any of the get ever survived after he killed their sire, they would have no trouble figuring out who Potter was and coming after him.

But he didn't think Potter would leave anyone alive when he attacked a nest. He was too careful and clever for that, as his expertise in destroying Caspar had shown. And Draco was the only vampire around at the moment.

These wards were doing nothing but holding him away from his Long-Desired.

He opened his mouth and showed his fangs to empty air, then hissed in exasperation. It was only eleven-o'clock, and he still had the rest of the night, but he doubted that was enough time to find a way around those wards. Besides, he was hungry, and had used up a lot of strength running to Potter's house. He would have to go away and come back with a plan.

He turned, and a painful light flared in front of him, throwing him back. He clapped his hands over his eyes, moaning in discomfort.

"What are you doing here, Malfoy?"

The scent. The scent filled his nostrils and draped over his body like a cloak. Draco's fangs ached as though they had just emerged from his gums, and he wanted to shake himself like a cat escaping from water. His mind sharpened, and suddenly he had dozens of new thoughts leaping through his head. He gasped twice and became himself again, far more fully himself than he had been since they defeated Caspar and he and Potter went their separate ways.

This is the reason vampires have Long-Desired, he thought, as his mind steadied. Not just for the power. Not just for the blood. It's the combination that makes us such successful predators. Our minds are faster and our bodies stronger in their presence.

He opened his eyes, which had fallen shut, and studied Potter. Potter stood cautiously a hundred feet away from him, his eyes narrowed and his nostrils flaring with dislike. Draco licked his lips and shifted closer.

Potter touched something around his throat. Draco didn't know what it was, except that it made a painful golden flash explode in front of his eyes, and he had to retreat a moment later, hand over his face and voice raised in a hissing protest. Potter showed no remorse as he repeated, "What are you doing here?"

Draco took several deep breaths—not that he needed to, but one of the master vampires who had made him, Thalia, had recommended that as a course for calming down, and that he could use. When he opened his eyes again, he struggled to see Potter through hazy sunset-colored afterimages. "You're not stupid," he said. "I don't care how often you have to play at it in your job or in front of a nest to keep them from realizing what you are. You know why I'm here."

"You want me." Potter spoke the words in a perfectly neutral, empty tone, as though he were talking of the weather on Mars.

"Of course. You're my Long-Desired." Draco thought it best to keep to simple, straightforward truths that no Gryffindor could deny. He was starting to see again, but he had no desire to experience Potter's weapon closer at hand. He dropped to a crouch on the heather and extended his hands, palm-upwards and empty.

Potter barked with laughter at him. "A vampire is never unarmed, Malfoy, so don't expect me to believe you are unless you wrench your fangs out of your mouth. And a crouch like that just means that you can come up at me faster."

Draco hissed aloud this time. It wouldn't avail to conceal his exasperation. Potter already knew he was exasperated, and exactly why. "What would convince you to become mine?" he asked. "I would gain so much from you—blood and power and companionship. It's not fair that you not receive as much as I do." The afterimages were clearing now, and he could see Potter's defiant stance and head-tilt. Even that just made Draco want him more, because he could smell the sharp tang of adrenaline driving Potter's pumping blood. "Only tell me what it is, and I'll make every effort to get it for you."

"Every vampire in Great Britain dead," Potter drawled.

Draco wasn't surprised. He had already seen how much Potter hated his kind. But he nodded and said, "I might be able to accomplish that. Most other vampires are tied down by a loyalty to their get or their sires that I have no reason to feel. It would take me years, but I could kill them. Or help you kill them."

There was a long, incredulous silence. Then Potter whispered, "Has it occurred to you that the deaths of all those vampires would have to include your own death?"

Draco stood, never taking his eyes from Potter's face. He could see in shadows or moonlight or pure darkness, and he would have seen the expression of pure disgust that made Potter's mouth bulge unattractively and widened his eyes in any of them. But he was no nearer to understanding it. "But I would be the one who helped you achieve these deaths. The weapon in your hand—"

"You forget how long I've hunted vampires," Potter said, his voice calm and ringing and deadly, "how well I know them. Trying to use a vampire as a weapon is like trying to use a viper as a whip. No."

Draco spent a few moments studying Potter, looking for some sign of yielding in his features. But there was none. In fact, he kept his chin stubbornly uplifted and his eyes deliberately haughty, as if he assumed that such an expression would put Draco off.

"I see that you don't understand," Draco said. "Then I must make you understand." He crouched and leaped at Potter. He didn't intend to hurt him; he simply wanted to show off his strength and humiliate the arrogant poseur a bit.

But Potter stepped easily to the side and twitched the thing at his throat again. Draco tried to cover his eyes. He wasn't in time, and the golden light seared his vision out. He landed safely and turned his head towards Potter, identifying his scent easily, but he wouldn't dare attack so impaired. Last time they met, Potter had been sick and weak from a long battle against Caspar and his nest, and Draco had been surging with new power and freedom, having emerged from Caspar's dominion. This time, they were too close to equal for Draco to be sure he would win.

"I understand," Potter said. "Vampires are greed, Malfoy—bred to be hunters and nothing else. That doesn't mean I have to surrender when one wants me. That kind of hunger isn't assuaged by surrender. You would demand more and more of me until I lost every ounce of my free will and self-respect." His voice held a peculiar loathing; Draco wondered if it was for Draco, or Potter himself, or perhaps Potter's imagined version of himself. "You can only get rid of it by ripping it out by the roots."

"It would be a bargain," said Draco, wondering if different words would make Potter see the matter differently. He licked around his fangs and wished he could see the expression on Potter's face. Then he would know whether he was getting through. "I don't want to destroy your free will and your self-respect."

"You might even believe that, in the depths of that scarred brain of yours." Potter's voice was tolerant, which made Draco's shoulders hunch and his skin prickle. He didn't want Potter to sound that way. Tolerance was the neighbor to indifference. He should be infatuated, enchanted, horrified, lured. Draco knew instinctively that he could work with any strong emotion. "It doesn't matter. What matters is that I know what would happen to me if I yielded to you."

A scrape. Draco knew it for a footstep. Potter had come closer. He tensed, ready to snatch him by the throat and drink again if he came close enough.

"Do you know what you are to me, Malfoy?" Potter whispered. "An enemy. An irritant. A predator. An alien. Another species." His voice sank and became a hiss that would have done Caspar credit. "Never, ever, a temptation."

The smell of the blood was driving Draco mad. Potter's adrenaline was high, his breath coming in short pants, and his heart was pounding so fast that Draco had trouble distinguishing one beat from another. There was so much passion in his voice, in his sheer presence, that Draco succumbed to temptation himself and made another grab.

He couldn't see the weapon Potter used—his vision had returned only in the form of drifting shadows against a gray background—but he felt it. It coiled around his fingers, a sting that quickly built to a fire, and then it yanked his thumb off. Draco cried out in protest and cradled his maimed hand close.

It infuriated him that, competing with the pain, came the feeling of Potter's magic, as contemptuously alive and strong as the heartbeat of an elephant, and it made his blood travel to his cock.

"Take easier prey, Malfoy," Potter said, and then his heartbeat vanished, indicating that he'd Apparated.

Draco eased back into the shelter of a small hillock and curled up, there to wait for his vision to return and his instincts to tell him what would heal his severed finger.

This may be harder than I thought.

But the scent of blood and magic lingered, and he knew whatever risk he had to run was worth it.

*

"No."

Harry paused. Then he laid the files he'd been holding carefully down and pushed them forwards until the people sitting across the table from him could see the description of the wounds on the bodies, which he'd underlined.

"With all due respect, Madam Stone, Mr. Austin," he said, "I think you can see that the attacks must have been committed by rogue vampires. That, in common with a Replacement Charm, accounts for every oddity of the cases."

"Many other things could, as well." Kevin Austin, the Head Auror, shook his head slowly from side to side. He had a thin moustache, sandy in color, which curled out into vague traces of hair above his lips. Harry focused on that to keep himself from hurling a torrent of abuse at Austin that would only get him reprimanded. "Experts have already assured us that the magic used at the scene comes from a living wizard, not from an undead one. We have developed new spells that will sense the difference between a wand and magic forced through the core itself."

Harry paused again. Whilst he thought the Ministry dangerously lax in many respects when it came to regulating vampires, he had to admit that they were good about gathering up their wands and ensuring that the vampires couldn't become even more dangerous. Any wizard or witch who was turned could not legally possess a wand. And most of them, as Harry had learned after intensively studying them, didn't want to in any case. They disdained such petty mortal possessions. They preferred to use their bare hands, their wandless magic, and their fangs to demonstrate that they were, in every respect, superior to humans.

"Vampires could still have got hold of a wand," he said. "You can't rule that possibility out."

"We already have," Madam Diana Stone said. She was Austin's second-in-command, a tall woman with a permanent harassed look on her face rather than the exhausted one most Aurors got. "We've checked all the records of every wand produced in Great Britain in the last ten years. Ollivander's given us a charm that permits us to check whether that wand is still with its original owner or not. In the case of the ones that aren't, they've been destroyed or are in Ministry custody." She leaned forwards and fixed him with eagle-like blue eyes that had the ability to make Harry squirm, though he tried not to show that. "Your 'theory' is less a theory than the product of your own obsession, Auror Potter."

Harry held his temper in check again. They do good work, he reminded himself. And you want to keep your job. It's not your fault that they won't take vampires seriously enough as a danger. They're too used to the ones who meekly come to the Ministry for their ration of blood every month. "I will admit that I'm prone to seeing vampires where there are none," he said, "but in this case, I think there are vampires here. Even the thefts make sense that way. Neither McFadden nor Gowan had particularly famous collections, but they were expensive and pretty. It doesn't make sense for mortal thieves to go to extreme lengths to steal those things, when they couldn't sell them for good prices on the black market. But vampires are greedy for greed's sake alone. They would steal them to admire them—"

"And so could mortals," said Stone, in a voice as heavy as her name.

Austin nodded. "There's simply too much here that the vampire theory does not explain," he said, "and too much that a theory of mortal thieves collaborating with each other does."

"Even the bites?" Harry demanded. "How do you explain the presence of no Dark magic or poison in the body, and yet those bites being there?"

"Some species of magical serpents in India leave similar wounds," said Stone. "We are investigating that angle." She gave him a pitying smile, which drove Harry closer to expressing his anger than anything else could have at the moment. "Auror Potter, you've captured plenty of dangerous criminals for us in the past, and I know that you're devoted to your work. But you should remember that an obsession sets limits on one's vision that the person with the obsession doesn't even notice. Not everything can be vampires. The use of a wand points to human wizards. That's what we'll continue to investigate." Her voice shifted subtly, and hardened. "And we have already arranged for you to be removed from both the McFadden and the Gowan cases."

Harry closed his eyes and gave a short nod. He could feel Austin and Stone watching him as he left the meeting room, but he kept his head held high. He wouldn't show them any trace of discouragement.

That was because he felt none.

As with every other time that rogue vampires had been causing trouble and the Ministry refused to admit it, Harry would have to go out and hunt the nest on his own. No one would appreciate what he did, because he could hardly tell them; the Department for the Regulation and Control of Magical Creatures was supposed to deal with rogues, and usually they tried to bring them in and convince them to register instead of killing them. Harry could be tried for murder if the right people got hold of him.

He didn't care. He understood vampires. They were as dangerous as any other beasts, hunting by instinct, but others were inclined to judge them less harshly because they looked human. And Harry had even heard some people who believed in vampiric instincts say that they couldn't help it, and should be excused their crimes.

Harry knew better. It was instincts, all right—instincts for greed, and cruelty, and delight in human suffering.

You don't reason with monsters like that. You destroy them.