Ok first this is a incomplete one shot you've been warned
Chapter One: A Stranger in the Dark
The rain lashed against the grimy streets of London, a relentless cold downpour pooling into the cracks of worn cobblestone. It seemed intent on drowning the city's filth. The city, alive with its usual chaos, remained oblivious to the fissure tearing through reality. Pools of water reflected the dim, flickering light of streetlamps, fractured and distorted with every passing moment. Somewhere in the shadows of an alley, a faint ripple of energy shimmered, barely noticeable to anyone who might've been looking — though no one was.
No one, except John Constantine.
He stood under the dim light of a flickering streetlamp, his soaked trench coat clinging to him, but he hardly cared as he lit a cigarette with steady hands. He took a drag, his eyes fixed on the alleyway across the street, his instincts prickling like they always did when something unnatural was about to happen.
For years, John had learned to listen to that feeling. It wasn't a gift, not really — more like a curse that kept him alive. Some called it luck, others called it a knack for being in the right place at the right time. John didn't bother naming it. He just trusted it to get him out of whatever trouble it got him into.
And tonight, it led him here.
John's eyes narrowed as, across the street, the alley shimmered, the shadows twisting unnaturally before snapping apart with a deafening crack. The sound echoed like thunder, and the air shifted — not the kind of shift that came with a storm, but one he could feel deep in his bones.
Magic.
Old, raw, and untamed. The kind of power that made the hairs on the back of his neck stand on end. He exhaled a plume of smoke, muttering under his breath, "Right, then. Let's see what fresh hell this is."
The rain poured harder as John stepped off the curb, boots splashing through puddles as he crossed the street. His cigarette sizzled and sputtered in the downpour, but he ignored it. In the alley, where the shimmer had been, a figure was sprawled on the wet cobblestones.
"Bloody hell," John muttered, his voice low, more annoyed than surprised. "What've we got here, then?"
The figure groaned, shifting slightly as he pushed himself up onto his hands and knees. He was young — too young for this kind of mess, John thought. His black coat hung heavy with rain, and beneath it, John caught glimpses of strange clothes. They weren't modern, but John wasn't sure they were ancient either. The kid's dark hair clung to his forehead, and when he finally looked up, John saw green eyes glowing faintly in the dim light.
"Oi, easy there," John said, raising his hands as the kid's grip tightened around something in his hand. A wand. Of course it was a wand.
The kid staggered to his feet, swaying slightly as he took in his surroundings. His voice was low and cracked when he finally spoke. "Where am I?"
"London," John replied, watching him carefully. "But I'm guessing that's not what you were expecting to hear."
The kid frowned, glancing around the alley like he was trying to piece together a puzzle. "This isn't… This isn't where I was," he murmured, more to himself than to John. "What happened? How did I get here?"
John took a slow step closer, careful not to spook him. "Beats me, mate. But if I had to guess, you didn't exactly plan this little trip, did you?"
The kid didn't answer, his eyes darting down to the wand in his hand. His grip tightened as he muttered something under his breath, and John felt the air around him shift again. Magic rippled outward, raw and unstable, and John took a deliberate step back.
"Oi, knock that off," he said, his voice sharp. "You're gonna set off every bloody ward in the city if you keep throwing your magic around like that."
The kid's head snapped up, his glowing green eyes narrowing. "You can feel it?"
John sighed, running a hand through his wet hair. "Yeah, I can feel it. And so can anyone else with half a brain. You're leaking power, mate. Might as well paint a target on your back while you're at it."
The kid blinked, his expression caught somewhere between confusion and suspicion. "You... You're a magic user?"
John smirked, pulling a flask from his coat and taking a swig. "Something like that. Name's John Constantine. Exorcist, demonologist, and occasional pain in the arse. And you are?"
The kid hesitated, like he wasn't sure whether to trust him, but eventually he said, "Harry. Harry Potter."
John raised an eyebrow. "Right. Well, Harry, looks like you've gotten yourself into a right mess. And lucky me, I get to clean it up."
Harry scowled. "I didn't ask for your help."
"No," John said, tucking the flask back into his coat, "but you need it. Trust me, kid, you're not in Kansas anymore. You're in my world now, and if you don't figure out how to keep that magic of yours on a leash, you're gonna have a lot bigger problems than me."
Harry's scowl deepened, but he didn't argue. Instead, he looked down at his wand, his expression unreadable. "I didn't mean for this to happen," he said quietly.
John exhaled another plume of smoke, his expression softening slightly. "Yeah, well, none of us do. Life's funny like that."
He turned and started walking toward the street, motioning for Harry to follow. "Come on. I know a place where you can dry off and get your bearings. And maybe, if we're lucky, we'll figure out what the hell brought you here."
Harry hesitated, his wand still clutched tightly in his hand. But after a moment, he followed, his footsteps splashing through the puddles behind John.
As they walked, John couldn't shake the feeling that this wasn't just some random accident. Whatever had brought Harry Potter into his world, it wasn't chance. The kid's power felt like it had been drawn here, pulled by something bigger than either of them.
John took another drag from his cigarette, muttering under his breath, "Just another bloody Tuesday."