Summary: There are parallel people in each world.
Spoilerwarning: HP- Book 5, FMA- episode 41
"He's dead," they'd said, repeated over and over as if to a child who wouldn't understand, "Sirius is dead. There's nothing you can do but mourn- He's in a better place."
Harry Potter, Boy-Who-Lived, sat on the concrete curb with hands in his pockets against the chill in the air and dimness of the evening, a book resting on his lap. He was thinking and running over past conversations, comments that stuck in his mind and wouldn't let go.
"He's dead," his memory says, in the voices of teachers and friends and the heavy tones Dumbledore had used, repeating endlessly, "he's dead he's dead he's dead he's dead-"
Harry remembered the way his godfather had fallen behind the veil, not a violent or painful death, but one... Anticlimactic. No body left behind to mourn over, no grave. There was a sort of memorial he'd made to Sirius hidden under the loose floorboard in his room, little more than an envelope containing the photograph of his parents' wedding with Sirius laughing in the background, and "Sirius Black" written on the envelope's front. Harry couldn't bring himself to do more than that.
Taking his hands out of his pockets, Harry closed the book and instead pulled out a piece of paper decorated with a detailed sketch of a circular pattern. He'd found it in a book in a muggle library, of all places- tucked behind an ancient encyclopedia on a disused shelf. It seemed to be a sort of dissertation on an entirely different way of doing magic. Rather than be centered on wands, it was centered upon vaguely circular arrays with varying degrees of fluidity. The book stressed that it was a science, not magic, and Harry had nearly laughed at that. Calling this odd form of magic a science was comparing the creation of fire to rocket ships. the comparison to science was obviously why it had ended up in a muggle place. After all, what use was alchemy to anyone?
Harry had at first begun to read it out of curiosity, and when he came upon a passage describing the application of alchemy in animating flesh and tissue, restoring life- That caught his interest like nothing else could. He'd at first tested out the minor arrays in the book, simple transformations, rock to dust to sand to rock in the center of a circle, with nothing more than a tap of his wand on the array. Each time he did it a slightly unpleasant tingle wound its way up his arm, but Harry disregarded it. These worked.
The other would work too.
Standing up, Harry put his book and paper away in the bag he carried with him, checking that everything was safe. It was, and Harry put out his wand in a signal for the knight bus.
Making his way to the Ministry of Magic was surprisingly simple. Access to the building itself was easy enough, with most wards still fractured from the battle that had raged here scant weeks before. Few people about at this hour of the night, or morning. However you wanted to look at it. The passages were deserted, and though he saw a few lit offices, Harry met no one in his descent to the department of mysteries. The door was, predictably, locked, but a quick sketch of a triangle within two circles with the tip of his wand and a slight tap made the lock melt away.
Harry stepped through the portal, passing things both incomprehensible and terrible, before entering the death room. It was just as he'd remembered, a horribly coliseum-like space with a raised dais as its only ornament. The floor bore several long cracks and shattered stonework from the battle here, as well.
Harry knelt, tapped his wand to the floor, and the pattern he'd been holding in his head painted itself across the floor in a wide swath. It manifested as a coil of black ink, unwinding into words and pictures that seemed to bear some hidden meaning. He also placed a small bowl in front of the gate, just far enough away not to hear the sibilant whispers that hid beyond the veil. It held objects he hoped would call sirius back to him- A long black hair Harry had found stuck on his robes, a bone Padfoot had been given to chewing on, a drop or two of his own blood. He hoped it would be enough.
Taking a deep breath, he tapped his wand against the floor. The array threw the room into crackling blue-white brilliance, the gate on the pedestal looking disturbed, tattered veil flying and twisting.
Everything faded to white.
It was too bright. That was Harry's first thought, trying to make sense of the world around him. The room blurred around him, dust in the air fading in and out of sight, and it took Harry a moment of thought to realize that his glasses had fallen off at some point.
He felt around the blurry, shifting shadows until his hand contacted something hard. Harry's hand closed around it, but it was the wrong shape. Not round, but... tapered? Confused, Harry felt around with his other hand, coming upon the cracked frames of his glasses with blind groping. He slid them on and gasped.
"Sirius-" he inhaled sharply, "oh god, Sirius, it worked-" He stopped, choked off, unable to say anything as a sob welled in his throat. He could feel tears dripping onto the floor but didn't care- Harry tentatively ran fingertips along Sirius' temple, brushing back the long black hair. The man's eyes followed him with confusion, eyes flickering with something unidentifiable.
"I didn't know if it would work or not," whispered Harry, reverent, "there were things mentioned about creations gone wrong- bodies without souls- twisted bodies that can barely live on their own. But you're perfect, just as you were..." He shook his head, as if clearing all unpleasant thoughts away. Harry looked down, realizing for the first time that Sirius was naked. He blushed slightly and pulled back, going to the bag he'd brought with him, Sirius' eyes following him every step of the way. Harry pulled out a pair of pants and an oversized shirt, both liberated from Vernon's closet.
"Here," said Harry, offering the clothes to his godfather, "for you. I brought them just in case." He gave a tentative half-smile, "May not fit you, though."
The man sitting on the floor took the clothes hesitantly, all the while looking at Harry as if there was something he just couldn't figure out. As he raised his arms to pull the shirt on, Harry gasped faintly and the damage he'd never before seen. His godfather's chest was crisscrossed with scars, the pale tissue forming large patches in places. The middle of his chest. His back. Half of his left side was too pale to be unmarked skin. If Sirius noticed him staring, he gave no sign. Harry thoughtfully turned around as the older man stood awkwardly to pull on oversized pants. When Harry turned back, he could see Sirius struggling to keep the pants from simply falling off bony hips. Vernon's shirt hung down nearly to Sirius' knees. Sirius looked down at the dilemma for a moment before carefully tearing a strip off the shirt and threading it through his belt loops. It may not have been the height of fashion, but it worked.
Sirius coughed, voice rough from disuse. He seemed to be trying to talk and finally succeeded in a rusty "where am I?"
"The Department of Mysteries," Harry answered, picking up his bag and making sure he still had everything he'd come with. The array had disappeared from the floor after its use, thankfully. "The Ministry of Magic."
"Ah," said Sirius, "and where is that?"
Harry turned to him sharply. "You don't know?" His eyes widened, and in a soft voice he continued, "you've lost your memory?"
"I don't know," Sirius looked puzzled and faintly anxious, shaking his head, "I remember- little bits of things, a castle, a dog, an explosion, a rat, a boy who was a wolf..." He closed his eyes, "It's all mixed up."
"I- no, never mind," Sirius smiled, "it's all right. Just- Who are you?"
Harry looked sad. "your godson. Harry."
"Oh," said Sirius, stopping there, unsure, "Harry..."
Harry turned his back, ducking his head for a moment. "It's all right," he said, "I- Let's get out of here, okay? I don't like this place." He glanced back at Sirius, then walked toward the main room. Sirius followed at a distance.
They met no competition on the way out of the building, halls just as deserted as when he'd gone in. Climbing the stairs, Harry had stopped to re-tie a loose shoelace and Sirius had gotten in front of him, just a little. Harry looked up at him, false moonlight striking Sirius' face from one side, and he realized something in the contour wasn't perfect. But it was Sirius. Did it matter?
Soon enough, Harry and Sirius had taken the quick way up to the street, and now were out in the open, real light shining down along with artificial halogen. Sirius looked wonderingly up at them, and Harry smiled and turned away, pulling out his wand to signal for the knight bus before realizing that it probably wasn't a good idea to do so. He let his wand-hand fall to his side, considering.
"Sirius," he said, "Do you think we-"
And all of a sudden, Sirius was there, pinning him to the rough brick wall with an almost insane look in his eye. Harry gasped and half-choked at the one had on his throat, other hand nearly crushing his ribcage, and how can Sirius be so strong, it's crazy-
"Harry," Sirius purrs, low and deadly, "I owe you. You freed me, and for that I'm thankful..." The hands clench tighter, and there's a strange crackling wave spreading through Harry's body from the contact points. Sirius tosses his head to the side and it's all wrong because Sirius would never condescend to purr and there's a red marking just under Sirius' ear, a dragon and a star-
"But," Sirius says, a sharp-toothed, insane grin on his face, "I don't like owing people."
Harry can't breathe, he can feel the sharp edges of the brick wall behind him digging in and his body feels all too hot and too cold at the same time. His eyes nearly roll back in his head, but he brings up the wand in his hand just the same, trying to cast a spell.
It doesn't work. It's not that he can't cast like this, there's just nothing there, no magic to draw on, gone as if it was never there, and a page of the book he'd found pops into memory. Equivalent Trade, it had said, to get, you must give-
No. It couldn't be. No-
"Sir...ius..." he pants, "why?"
Sirius squeezes even harder, though making sure not to snap the boy's neck. He wants him alive, if only for a few seconds more...
"My name," he leans in and grins, and now Harry can see that the face is all wrong and it's not Sirius and what has he done- "Is Kimberley."
There is a story of an explosion in the warehouse district on the news the next morning, but no one at Privet Drive bothers to care why Harry hasn't come home.