Warnings: death, but nothing graphic, very light language
Prompter: christywild
Disclaimer: I don't own Harry Potter, Castle or any related characters. Harry Potter belongs to JK Rowling, and Castle belongs to ABC and its creator—i.e. not me.
Author's Notes:
This is a very belated wishlist-fic story. The prompter is noted above, and I hope she enjoys what I do with this! The actual prompt is serving as the story's summary. This is, also, a fill for the hc-bingo square, forced to hurt somebody. Also, I'm not caught up on Castle… in fact, I lack about, uh, 6 or so episodes from being done with Season 3. So, I'm not going to pick a specific setting, just know that it's somewhere before where I left off. And if anyone is terribly out of character, I apologize. It's been a while since I've been in this fandom—speaking mostly of Castle. Hope everyone enjoys!


Supposed To

Kate Beckett leaned forward in her desk's chair, her hands grasping the hot mug of coffee like it was barely lukewarm—despite the tendrils of steam rising off of it. Castle sat on the edge of her desk, inching closer to her every so often. A look of deep concern colored his features, and one could tell just by looking that he desperately wanted to reach out and lay a hand on Beckett's shoulder. Eventually, he managed to drag his eyes up and away from the sullen homicide detective and scan the room around them.

The 12th precinct was fairly empty, most of the detectives having decided to call it a day after their most recent stack of paperwork had been done and filed. Esposito and Ryan had been reluctant to go, but the two other occupants left, currently, in the room with Castle and Beckett had persuaded them to do so. Castle had a feeling that persuade might not have been the right word for it, but he didn't want to think about it. Instead, he leveled his eyes on the pair—a young woman, probably no more than nineteen or twenty, and an older man whom Castle could guess was old enough to be the girl's father... but was sure wasn't.

They were British, the two of them, and had arrived about three days ago in New York City. The man was tall, but not towering, with long black hair reaching to his shoulders that was a tad on the greasy side. His skin was a sallow color, and Castle had an itch to ask him if he were perhaps sick or something. The girl, however, looked much more robust. Her wild brown hair had been tamed down into a braid, reaching mid-back, and her heart-shaped face was locked on Beckett, her brown eyes narrowed in quiet concern. These two had introduced themselves as Severus Snape and Hermione Granger, and Castle and Beckett had been quick to find out that there was much more to them than what met the eye.

"It's not your fault," Hermione said, kneeling down so that she could lock eyes with the downturned Beckett. "It was the Imperius Curse. You couldn't help it."

Castle looked to Snape, whose face was nearly unreadable. He had his gaze on the young witch, his lips pulled tightly together. Castle's brow furrowed.

"Kate was cursed," he said, trying to work it over in his mind.

Snape sighed and nodded. "Yes. Imperius is one of the three Unforgivable Curses."

Castle bobbed his head. "Along with the, uh, Killing Curse, right?"

"That's correct."

"I killed that guy," Beckett murmured into her coffee.

She looked up, searching each set of eyes she came to before finally turning back to Hermione, who shook her head.

"It wasn't you. Someone forced you to do it. That's what Imperius does."

Beckett nodded and forced a scalding sip of coffee down her throat. "I could hear someone… Someone telling me to pull the trigger."

The detective seemed to come back to herself for the second time since what had transpired earlier that evening. She set her mug down on the desk behind her. She stood and paced a small path before the witch and wizard. She shook her head, running a hand through her hair.

"So, let me get this all straight. Our murderer… he's a wizard, too? And he killed those people with magic, and then cursed me to kill someone else," she said, ticking the events off on her hand.

Hermione rose to her feet and exchanged a look with Snape. Snape sighed.

"It's a long story, but, yes. That, truly, is what happened," he said.

Castle slid off the desk, forcing Beckett to stop her pacing as he was now in her best pathway. The author darted glances back and forth between the two before he finally pursed his lips.

"You know why he was here, don't you? The guy doing all this killing?"

Hermione was the one to answer, her tones solemn and sad.

"Yes. In fact, Severus and I came here to stop him as soon as we realized what was happening."

"And what did happen?" Beckett demanded. "Back there, in the warehouse? What the hell happened?"

Snape motioned to the chair Beckett had formerly occupied while he slid into the one matching the desk he was leaning on. Hermione remained standing while Castle sat back down on the corner of Beckett's desk.

"Let us explain," the wizard said.

Beckett all but dropped back into her chair. "Damned well better. But something tells me that my boss isn't going to believe all of this."

"That is highly unlikely," Hermione laughed mirthlessly.

#

Three Days Earlier

"Oh Merlin," Hermione breathed, her words forming fog in the chill of the city's night air.

Red and blue lights lit up the brick walls of the alleyway, and a small crowd had formed at the police-made barrier. Reporters and general citizens had flocked to see what had caused the commotion so close to them, and it had been hell for Hermione to fight her way to the front. But she was there, her eyes wide. She shook her head, looking up at Snape, who stood statue-still beside her.

"This isn't supposed to happen," Snape muttered.

Hermione felt her heart droop in her chest. "A lot of things weren't supposed to happen. You weren't supposed to be alive anymore, remember?"

He gave a wry grin at that. "Yes. Imagine your surprise when you realized that the person who was helping you on this trail was me."

"One day, you'll have to tell me what really happened the night Nagini attacked you."

Snape shook his head, discreetly lifting a finger and pointing to the corpse on the ground several feet beyond the yellow-and-black tape.

"When it's important. Right now, that is what our concern is. Do you see, Miss Granger?"

Hermione turned her attention back to the circle of law enforcement that had gathered around the fallen body. A woman with chestnut colored hair stood beside a brown-haired man in a black overcoat. The woman was clearly a detective, but the man seemed to be there for the sole purpose of being a slight annoyance to her. But it was the body at their feet that Hermione was sure Snape meant.

It was a man, probably no older than his late twenties, and his skin was ashen. His eyes were frozen open, and his mouth formed a little "O" of surprise. His arms and legs were crooked out in various angles—like he had tried to run away as fast as possible and been stopped mid-action.

"The Killing Curse," Hermione said.

Snape nodded. "But there's something else. Can you see his mouth?"

Hermione squinted against the endlessly flashing lights. But there was really no mistaking it. Around the poor man's mouth was a redness that looked like something in between raw and burned skin. The "O" that the mouth formed was not of surprise… that was the look left when someone sucked your life away.

"He's one of Mulciber's victims."

"On the receiving end of his bastardized version of a Dementor's Kiss."

Mulciber was a dark wizard who had survived the Battle of Hogwarts, and now, he sought to survive more than that. Hermione likened it to him taking up Voldemort's mantel, as it seemed that he was looking for a way to achieve endless life. Rumor had it that he had taken some form of injury during his fight, and was slowly dying anyway. That was, until he discovered a way to create his own Dementor's Kiss. By sucking the souls out of unsuspecting men and women, he extended his own life. Hermione had first stumbled across the strange bodies left in his wake about a year and a half ago, during her first job with the Ministry.

Immediately, she had set herself to the task of discovering the cause of death—and the origin of the deaths—that were popping up all over the globe. Her superiors had, at first, thought her a bit mad, but after the bodies started to make a steady climb into the double-digits, they couldn't deny that she might be on to something. And then, one day, she had received a letter. The writer was unknown to her, but it encouraged her to keep up the search. That she had been right and something was horribly amiss. For six months, she and her mysterious pen pal had conversed and shared all of what each other had learned about the case. Their first physical meeting had been in Albania, and it was then that Hermione had learned the truth behind her pen pal—or, at least all that he had been willing to share. Severus Snape, seemingly back from the dead, had been trailing Mulciber just as she had. Always two or three bodies behind, they had finally surmised that his next hunting grounds would be in America, in New York City. And now, as the two of them stared at the first body to arise that had obvious connections to Mulciber, they knew that they were right. And that they were finally caught up.

"So, that's one victim. He tries for at least three or four within a fortnight," Hermione noted, looking up at Snape.

Snape nodded. "We just need to figure out who he will attack next."

Hermione's eyes dimmed as she pulled her lips into a tight frown. "It's always muggles or muggle-borns."

Snape's brow furrowed, and he rested a tense hand on the young woman's shoulder. "Let's go. We've got work."

#

"Halloween already?" Castle noted as he gazed down at the victim's body.

The identification found in the man's pockets labeled him as Marshall Merryweather, and he was only twenty-eight years old. Now, though, all signs of his youthful appearance had been diminished by his ashen skin, O-shaped mouth, and a red, rash-like wrinkling around his lips. Beckett, who knelt beside the victim, shook her head as she gazed up at Castle.

"I don't get it. Unless our toxicology report comes back with something, it looks like he just died. Like his body just up and quit on him," she grumbled, rising to her feet.

"It looks like something was sucking on him," Castle said, pointing to his lips. "One hell of a hickey, I'll tell you that."

Beckett rose to her feet, rolling her eyes—and careful to keep the motion hidden from the gathering storm of reporters.

"Yeah, because that's how he died. He was sucked to death. Get serious," she groaned.

Castle shrugged. "All right, fine. But I don't know of any poison that does that to a person."

Beckett took off her blue examiner's glove and shoved it into her pants' pocket. Then, crossing her arms, she had no choice but to nod in agreement.

"You've got me there. But maybe the lab will have something for us."

"Yeah, but, honestly, I think we ought to investigate Marshall more closely. Whoever did this to him… there was some serious disdain going on."

Beckett grinned. "No, I thought we'd just go on vacation while we wait for the results. Forget all this murder nonsense."

"Well, the Bahamas are beautiful this time of year," he said.

The detective shook her head and grabbed up the evidence bag containing the deceased's wallet.

"Let's go."

#

Thankfully, New York City had a strong wizarding community. Snape and Hermione were able to rent a room over a magically-inclined pub with no problem at all—though, honestly, they only had the funds for one room, but the two had grown rather used to each other's company during their travels to find Mulciber. They had taken in a small supper in the pub, and then retreated to their room with all the information they had on Mulciber's murders spread out before them on the table. It had been almost twenty-four hours since the first body had been discovered, and now Hermione was near the point of pulling all her hair out.

"There's got to be a pattern. My mother has read enough on serial killers and the like that I know that much!" she all but screeched at the pile of parchment before her.

Snape arched a brow. "Your mother's favorite pastime is reading on serial murderers?"

Hermione sighed. "Yes, morbid, I know, but she's actually gotten quite good at figuring out motive and patterns and such."

Tossing a folded piece of parchment to the center of the table, Snape gave a huff of annoyance.

"Then perhaps we should have contacted her for this."

Hermione shook her head. "There's something here. Some reason he kills the people he does."

"We've already established that. Muggles and muggle-borns, because he's a purist. And never children. And I'd wager he doesn't bother with children because their souls have not gotten old enough to offer him any real sustenance."

Hermione's stomach churned at that thought, and she pursed her lips. But that was the price for hunting down a crazed dark wizard. Sometimes, the harsh truth was just what you had to work with.

"Okay, so maybe it's not who he kills. Maybe there's something else that we're missing," Hermione noted, pulling forward the parchment stack that contained the notes on Mulciber's earliest killings.

She tossed Snape the notes on the next set of killings, and began to pour over the notes she had in her own hand—for the millionth time, it seemed. Her eyes were growing heavy and tired, and they even stung a bit as she forced them to keep reading. She read the page in her hand several times over, reaching the bottom only to rise back to the top. Finally, however, a set of words jumped out at her.

"Severus," she asked, "where did Voldemort meet Professor Quirrell?"

Snape's brow furrowed. "In a forest in Albania, I believe."

"That's where the first killing was. And then second was another place in Albania that Voldemort was known to have frequented."

"We've already covered that. He's not following exactly in Voldemort's footsteps. Voldemort never left Europe, and some of the places that Mulciber has killed, even in England, Voldemort has no connection to."

But Hermione was shaking her head, reaching across for more notes. "You're right about that, but there is a significance! Look at all these places… what do they have in common?"

She shoved the piles of parchment under Snape's nose, tapping at the locations of each different killing. Snape's eyes narrowed, then widened, as he realized what Hermione was talking about.

"They're all magically inclined areas. Areas where history—either muggle or otherwise—has left a strong magical residue behind," he breathed, clearly surprised.

"Maybe he needs the extra power to perform his spell," Hermione ventured.

Snape smiled up at her. "You might have just done it, Miss Granger."

"When are you ever going to start calling me Hermione?" she laughed.

His smile shortened to a grin that seemed to promise more behind it. "Soon enough."

Hermione shook her head, clearing her throat. "Let's figure out where he'll go next. New York has a lot of historical sites, some of which unknown even to its citizens."

"He'll try to pick a magically significant spot. You'll notice that the killings that took place on muggle-significant spots are few and far between," Snape said.

"Right."

#

"No poison, no wounds, no illness. Practically no cause of death," Beckett said, typing furiously into her computer.

Castle sat on the edge of her desk, his eyes narrowed down at her.

"I'm telling you, occult," he said.

Beckett groaned and moved her hands off the keyboard to grip the desk like she was gripping someone's throat.

"I've told you before, Castle, this isn't related to the damn occult!" she growled.

Castle held up both his hands. "Whoa, whoa. Just speculating."

Beckett ran a hand through her hair. "Well, could you at least speculate on something plausible?"

"Where's the fun in that?" Castle replied, flashing a dazzling smile.

Beckett shook her head, turning her attention back to the monitor.

"Look at all these deaths. There are cases all over the place, usually three or four victims and then this guy skips to the next town to do it all again. And there's no common thread between the victims, except that there's no children. Otherwise, the men and women are all very different from each other. But all killers have a pattern they follow. This guy has one; we just need to find it."

Castle leaned in over her shoulder, his eyes scanning the various case files as the detective flashed them up on the screen. She was right. The men and woman were varied in working class, age, and ethnicity. A factor the author got to relive as Beckett endlessly swept through each file. Finally, on the third or fourth go round, Castle laid a hand on her shoulder to stop her.

"Maybe it's the place, not the person," he muttered.

She glanced up at him. "What do you mean?"

"Look," he said, pointing out the location of the body in the latest case file Beckett had up. "I recognize this place from a report Alexis did once. It was about unexplainable events. Every one of these places, I'd guess, has had some sort of something happen to it that has yet to be explained, but it was big enough to go down in history."

The detective's eyes lit up as she began to jot down the names of all the places in all the files. Then, it was on to a search engine, typing in each one in turn. A smile started to spread over her face as she realized that Castle had been right. A seemingly unexplainable event—from floods, to missing persons literally vanishing as they turned the corner, and more—had taken place at each location.

"We can guess where this guy will strike next," Beckett said breathlessly.

Castle grinned. "See what I mean?"

She arched a brow up at him. "What are you talking about?"

"Mysterious floods. Vanishing people into thin air. Occult. I was right."

She only rolled her eyes.

#

Downtown New York had a warehouse. A very old warehouse that, sometime back in the mid-thirties, had spontaneously combusted. Investigations never did find a source to the fire, and had only just managed to save the building. At least, that was the extent the muggles knew of the place. The wizarding community, however, knew that a bunch of drunk, freshly graduated students had been partying, and, well… fire had happened.

Hermione and Snape had apparated there as soon as they realized that this would most likely be the place for Mulciber's next attack. Wands at the ready, they had landed right in the center of the broken down, wide-spaced warehouse. From there, they had taken to the shadows, and waited.

It didn't take long. The sun had set, and just moments later, several of the barrels located about the floor had fire spring to life in them. The entire center of the warehouse was now lit as bright as day, whereas shadows trailed long on the outskirts of the circle of barrels. It was to the center that Mulciber now led his soon-to-be victim, a man who looked to be thirty or so years old.

"Please," he pleaded as Mulciber—his thick, olive colored hand wrapped in the poor man's blond hair—shoved him toward the center of the lit circle. "Please! I'll give you anything you want! Just don't hurt me!"

"Shut it!" Mulciber growled, followed by a long, hallow cough.

He shoved the man from him, and he landed against one of the lit barrels. He hissed from the heat of it, turning to face his abductor.

"I don't have much money," he said.

Mulciber, his eyes the color of dead coals and sunk deep into his head, laughed.

"It's not your muggle money I'm interested in," he said.

The former Death Eater straightened himself—and that looked like it took great effort—and pushed back an unruly lock of his midnight black hair. He aimed his wand at the muggle's chest.

The man, for his part, seemed confused. He shook his head, his hands instinctually raising up to mid-chest.

"Look, I don't know what that stick is supposed to do, or why you jumped me, but nothing crazy has got to happen here. If you let me go, I won't say a word. I swear."

Hermione exchanged a glance with Snape. He nodded once, motioning for her to move so that she would come up behind Mulciber. He would take the direct approach, and the two parted ways. Meanwhile, the dark wizard was still toying with his victim.

"I could care a less what you spoke of, you filthy muggle. But, as it is, that isn't a concern. You'll be dead in a moment," he menaced.

The man whirled on heel and tried to run, but Mulciber shouted a spell at him. Like a puppet on a string, the muggle flew backward, landing on the floor at his attacker's feet. From across the way, Hermione caught sight of Snape. Her former professor held his wand aloft, and moved to step out of the shadows. However, he stopped just short as another voice shouted, "Freeze!"

Hermione swallowed a gasp as the chestnut haired detective from several days ago and the dark haired man emerged from somewhere around the entrance of the warehouse. They only just managed to miss Snape as he crouched down behind a shadowed beam. Mulciber laughed, and his intended victim was roused once more, pulling himself up to a sitting position.

"Thank God. He's got some sort of voodoo or something!" the muggle shouted at the officer and her companion.

A strange look of strangled humor passed over the man standing beside the detective, but he forced it back down out of sight.

"Detective Beckett, NYPD. And I said freeze!" she shouted at the dark wizard.

Hermione's heart thudded in her chest. This wasn't good. This wasn't good at all. Her eyes searched the darkness across from her as she tried to locate Snape. But Detective Beckett and whomever that was with her was blocking the young witch's view.

"Do you really think you can stop me?" Mulciber growled.

Beckett moved her gun just ever so slightly. "Yeah. I think I can. Now let that man go."

Mulciber lowered his wand, the very picture of compliance. Hermione could almost feel the flood of relief off the man as he rose to his feet. However, in a flash, Mulciber had his wand up again, aimed at the detective.

"Imperio!" he cried.

"Bloody hell," Hermione muttered as both she and Snape emerged from their hiding spots.

The man with Beckett seemed more than a little alarmed, but Hermione and Snape didn't have time to care. They both leveled their wands at the dark wizard, hoping to stop him before his orders—whatever they may be—were played out through Detective Beckett.

"Stupefy!" Hermione cried, as Snape shouted, "Incarcerous!"

But it was too late. Mulciber jerked his wand toward his being, and the muggle caught in the crossfire froze, eyes wide like an animal in headlights. Detective Beckett—the struggle horribly clear on her face—raised her gun and fired a single shot. It hit the poor muggle right between the eyes, and he felt to the dirty cement with a thud. But Hermione and Snape's spells had done their work, immobilizing Mulciber and binding him in ropes. Hermione muttered another spell, sending his wand flying from his hand.

Beckett seemed to come back to herself, and she dropped her gun in horror. She gazed wildly around, eyes finding all three of them, but finally resting on the man she had brought with her.

"I… I didn't mean to. I tried to stop. It was like… like—" she stammered.

"Like you were made to," Snape said, reaching down to jerk Mulciber up by the ropes. "That's because you were. He cursed you."

Beckett's eyes widened as they landed on Snape. "Cursed me? That's not… that's not possible! Who are you two?"

The man had approached Beckett now and wrapped an arm about her. He looked up at both Hermione and Snape, and without words, confirmed for both of them that he believed what they had said. Hermione's brow furrowed.

"Is there someplace we can go? So we can explain what happened?" she asked gently.

"Back to the station, I think would be best," the man replied.

#

"So, he was sucking their souls out… to prolong his life?" Beckett asked, a hint of disbelief in her tones.

"Detective, you were just forced to shoot someone in cold blood. Do you truly doubt what we have told you?" Snape snapped at her.

"Severus," Hermione chastised, but Beckett held up a hand.

"No. He's right. But… what now? I mean, I killed someone, with no cause. How am I going to explain all this to my superiors? How am I supposed to be okay with it?"

"Because it wasn't you. Honestly and completely. That's how you should be okay with it," Hermione answered.

Castle nodded. "She's right, Kate. I saw what happened, that look in your eyes. You didn't do that. That… uh, Death Eater did."

Beckett seemed to drink all that in before she finally nodded. "And my superiors?"

"We'll handle that, don't worry. Won't harm them a bit," Hermione said.

"How? I mean, how will you handle that?" Castle asked.

"We'll erase the events from their memory, and replace it with false information that should satisfy everyone," Snape explained.

"Even us?" Beckett asked.

Snape and Hermione exchanged a glance.

"Not necessarily. By law, we should… but… how well can the two of you keep a secret?"

"I'm a cop," Beckett answered.

"And I'm a bestselling author. Do you know how many times people have tried to get me to leak parts of my novels online?" Castle laughed.

"Then we won't. But you mustn't speak of this, you understand?" Hermione asked.

"Of course. Who'd believe us anyhow?" Beckett groaned.

Snape sighed. "Then it's settled. We'll retrieve Mulciber and transport him to the proper authorities. Then, we'll return and deal with the memories of your superiors."

"Sounds great," Beckett said dully, standing. "But, um, what if this happens again… if there's another wizard-related crime or whatever?"

Hermione smiled. "My parents have a telephone. They're muggles—ah, non-magic folk. I'll leave it with you, if you should ever need us, or someone we know, again."

Castle laughed. "Useful. Say, um, before the both of you go… what kind of magic can you do? I mean, are there limits?"

Beckett shook her head. "Never mind him. Just go."

And with that, Snape and Hermione vanished with a loud pop. Castle grinned.

"Okay. Now that was awesome."