Harry Potter: The Greatest Assassin

Harry blinked, as he looked down at the floor, not wanting to stare at the two people sitting across from him, he didn't expect, this to happen, let alone that anything was special about him.

He moved his right arm to his left, as he started to scratch it, and looked up to see Tristan's worried face and the woman he was introduced to as Rosa, cold but gentle.

They had spent the 2 hours explaining to him, and to say it was unbelievable was an understatement, as he looked at both of them. Just yesterday, he came out of a bad situation, and now this was happening, he didn't know what to do as he just chuckled, it was a happy one, it sounded a bit hollow, and maybe there was more as he looked up at them

His green eyes met them, and for the First time, Rosa flinched, his eyes were green, just like hers and even Tristan's, but it was lighter Green almost like that Curse.

But Rosa can't believe it, that things was notuvg but a Myth, as she calmed down.

"Yes Harry, you are a Wizard".

Harry blinked again, as if doing it enough times would change the truth.

"A wizard…" he repeated, voice barely louder than a breath. "Like… with a wand? And magic spells?"

Tristan smiled softly. "Exactly like that."

Harry leaned back in the chair, fingers twitching against his sleeves. His eyes scanned the modest apartment room again—like the familiarity of it might anchor him to something normal. It didn't.

"You're telling me…" he began slowly, "...that I can do magic?"

Rosa nodded. "Magic that's likely been asleep inside you for years."

Harry let out a laugh—short, strained, and utterly unbelieving. "So, is that why weird things happened around me sometimes? Like the glass disappearing at the zoo, or Dudley's hair turning green once?"

"That's exactly why," Tristan said, his voice careful, encouraging.

Rosa sat forward slightly. "Magic often manifests in children when they're scared or in danger. You've been… under a lot of stress, Harry. It's a miracle your magic didn't lash out worse."

Harry's hand clenched his sleeve tighter. "You mean I could've… hurt someone?"

"No," Rosa said firmly. "You protected yourself. There's a difference."

That silence returned again—heavy, uncomfortable. Harry could feel it, like pressure behind his eyes.

"I thought I was just… broken," he said quietly. "I thought maybe something was wrong with me. That's why they kept me locked up."

"They were wrong," Tristan said at once. "There's nothing wrong with you, Harry."

Harry didn't answer. His mind felt like it was swimming. A wizard. Magic. A world he'd never known existed suddenly opening up beneath his feet.

He looked at Rosa again. "You said there's a school. For magic."

Rosa nodded. "Hogwarts School of Witchcraft and Wizardry. You'll get your letter soon—it usually comes on your birthday, but special circumstances mean we're handling this earlier."

Harry's birthday. He never celebrated it.

"So, what happens now?" he asked, finally meeting both their eyes.

Tristan folded his arms, his face kind but serious. "Now, we help you adjust. You're safe now, Harry. That's the most important part."

Rosa stood up and reached into her coat pocket. "Actually… there's one more thing."

She pulled out an envelope—dark parchment sealed with a wax sigil shaped like a coiled serpent holding a sword in its mouth.

Harry took it slowly, turning it in his hands.

"What's this?"

Rosa hesitated for a moment. Then she said, "That… is something that belonged to your bloodline. A legacy."

Harry raised an eyebrow. "What kind of legacy?"

Her lips twitched into something between a smirk and a sigh.

"One that makes you a very interesting wizard, Harry Potter."

Harry looked at the Letter as before he opened it, he spoke. "Tell me something, is this also magic"

Rosa blinked as she spoke. "Will, depends on what you are going to show me"

Harry made a fist, as the Mark of Beelzebub was active, and the Beelzebub blade was summoned in Harry's right arm. As the dark blade was there, Tristan's jaw dropped, seeing the power and Rosa's eyes went wide as she looked at Harry's arm.

Rosa spoke in shock as she looked at Harry. "No way, you have one of his Seven"

Harry blinked as he spoke. "7?"

Rosa looked at him as she spoke. "I will explain that to you later, tell is it's name Lucifer?"

Harry blinked as he spoke. "No, I call it Beelzebub, just felt right".

Rosa spoke in her mind. "It's Gluttony, not Pride, that's Better I guess, This proves one theory, Lucifer wasn't a Sword".

Harry looked down at the blade in his hand, its surface black as pitch, humming with a quiet hunger that only he seemed to feel.

The room was frozen.

Tristan stared at the weapon as though it might come alive and strike at any moment. "Harry," he finally said, voice cautious, "where did you get that?"

Harry hesitated. "A few weeks ago. In an alley. A white snake led me to it."

That didn't help Tristan's expression.

But Rosa… Rosa stepped forward slowly, eyes locked on the blade with a mix of awe and dread. "Beelzebub," she whispered, the name falling from her lips like a prayer—or a curse. "That's one of them. One of the Seven."

Harry tilted his head. "You said that before. Seven what?"

She looked at him, all teasing and warmth gone from her voice. "The Sin Weapons," she said. "Created during the Golden Age of Magic—before the Statute of Secrecy, before Hogwarts. Seven sentient weapons, each embodying one of the Seven Deadly Sins. Each bound to a chosen wielder through blood and fate."

Tristan looked between them. "Wait, what?"

Rosa didn't look away from the sword. "The blades aren't supposed to exist anymore. Most historians think they were myths. But the Ministry… they have a vault of restricted knowledge. I've read things—scrolls, broken stone records. Each Sin Weapon is a soul-bound construct—magic beyond modern comprehension. Only one wielder at a time. And only the sword chooses."

Harry looked back at the blade. It pulsed once in his grip, almost like it was listening.

Rosa's voice softened, but her eyes sharpened. "You said it's called Beelzebub?"

Harry nodded. "I didn't name it. It just… felt right."

Rosa exhaled slowly. "Beelzebub is the Sword of Gluttony. A consuming hunger. Not always for food, but for strength, power, even memory. It's not evil—but it reflects the will of the one who wields it."

Harry swallowed. "You thought it was Lucifer at first?"

Rosa gave a tight nod. "Lucifer is the rumored name of the Sword of Pride. That was the most feared of the Seven. But if Beelzebub chose you… then maybe the stories were wrong. Or maybe…" She looked at him, eyes narrowing just slightly. "…maybe the cycle has started again."

Harry dispelled the sword, and in a flicker of shadow and light, it vanished back into his skin—leaving behind only the faint black mark.

Tristan finally found his voice. "So, what—he's got an ancient magical sword living in his arm?"

"Yes," Rosa said bluntly. "And that means we have less time than we thought."

"Time for what?" Harry asked.

Rosa hesitated.

Then she handed him the letter again. "Open this. Then we'll talk about Houses, bloodlines… and why the Slytherin Clan is watching you."

Harry looked down at the envelope. The coiled serpent on the wax seal gleamed faintly in the light.

And this time, he broke it open.

Harry unfolded the letter and began reading aloud, his brows furrowing as he went.

---

Dear Harry James Potter,

I hope this letter finds you well.

It is I, the current Head of the Slytherin Clan—Lord Slytherin.

It has come to our attention that you are one of us. And not just any member… but a rather important one. According to the ancient blood seals, your lineage has reawakened a forgotten House within our clan:

The House of Hydra.

As such, we formally extend an invitation to join the Slytherin Clan, as both a member… and the new Heir of House Hydra.

Please don't panic.

Sincerely,

Lord Slytherin

(The one with the long green robes and dramatic flair. You'll know when you see me.)

---

Harry blinked. Once. Twice. Then looked up.

"…Okay. I have questions," he said, holding up the paper like it had personally insulted his common sense. "What the bloody hell is a Slytherin? And why does it sound like a brand of expensive cologne?"

Rosa opened her mouth—then closed it.

"…It's complicated."

Harry squinted. "Try me."

Tristan, from the side, whispered like someone narrating a fantasy anime trailer:

"Long ago, in the Golden Age of Magic, there were Four Great Clans—each descended from a Founder. Slytherin was one of them. Snake-themed. Drama. Vibes. Way too much green."

Rosa shot him a look. "Stop that."

Harry blinked again.

"So you're telling me… I'm part of some ancient snake cult aristocracy?"

Tristan raised a finger.

"Technically, yes."

Rosa, pinching the bridge of her nose, finally explained:

"Slytherin is one of the original wizarding bloodlines. Powerful. Influential. Mysterious. And—somewhat unfortunately—fond of theatrics."

Harry just stared at them both.

"…Is that why this guy calls himself Lord Slytherin? Does he carry a snake cane and speak in riddles too?"

Tristan burst out laughing. "He absolutely does."

Rosa looked ready to melt into the floor. "He's still your… sort-of-grand-uncle-by-blood-ritual."

Harry tilted his head.

"Right. So. To summarize: I'm a wizard. I have a demon sword. I'm a noble snake prince now. And apparently, my entire bloodline is based on serpentine fashion statements."

Rosa looked at Tristan.

"He's taking this better than expected."

Harry held up a finger.

"No, no—I'm internally screaming. This is just my trauma response."

After a few minutes or explain who the 4 Founders were to Harry

Harry furrowed his brows, still processing everything, then glanced at the letter again.

"So… is this Lord Slytherin guy the same as that Salazar Slytherin from the history books? You know, beard, snakes, founder of Hogwarts, all that dramatic jazz?"

Rosa shook her head quickly.

"No, no—definitely not him. Lord Slytherin is a descendant. A direct bloodline heir, but… centuries removed. The original Salazar's been dead for over a thousand years. This one just inherited the name and the overly theatrical fashion sense."

Harry looked down at the name again.

"…He signs his letters like he's starring in a Shakespeare play."

Tristan snorted from the couch.

"Wait till he gives a speech. Man starts every sentence with 'As foretold by the Prophecies of my House…' even when ordering lunch."

Rosa groaned. "He does not! …Okay, he did that once."

Harry raised an eyebrow.

"Right. And what about the other three? If there's a Slytherin Clan, then I'm guessing the others—Gryffindor, Ravenclaw, Hufflepuff—have their own weird snake-free versions too?"

Rosa crossed her arms, nodding reluctantly.

"Yes. They exist. All four Founder Clans survived in some form, passed down through ancient magical bloodlines. Some stayed in Britain. Some spread out. Some went underground. Each has their own traditions, their own internal factions, and… politics."

Harry blinked.

"Okay, so… when do I meet them?"

Rosa hesitated, then let out a breath.

"When the Clan Ball starts."

Harry tilted his head.

"…That sounds like a magical prom."

Tristan gave him a side grin.

"More like a high-stakes aristocratic power-play with fancy food and passive-aggressive wand duels."

Harry stared at him.

"…I was right. It is prom. But worse."

Rosa just sighed and patted his shoulder.

"Don't worry, we'll get you a decent suit. Just… try not to summon your demon sword in the middle of it, okay?"

Harry muttered under his breath.

"No promises."

Harry looked between Rosa and Tristan, tilting his head.

"So… what about Lord Slytherin then? Which house is his family from?"

Rosa's expression shifted—just a little. A touch more respect in her tone.

"Ah, him. Lord Slytherin's family doesn't belong to any of the Ten Major Houses or the Three Monitor Houses."

Harry blinked. "Wait, what? Then where do they belong?"

Rosa gave a small smile. One that held both awe and caution.

"They belong to a different category altogether. It's called the One King House."

Harry frowned. "One King? That sounds like a final boss title."

Tristan leaned back on the couch. "That's not far off."

Rosa continued.

"The name of that house… is The House of Basilisk."

Harry opened his mouth… then paused.

"Basilisk. That sounds weird… What is that? A kind of wizard?"

Rosa smirked slightly.

"Nope. A creature. A deadly one. The Basilisk is the legendary serpent said to kill with a single glance."

Tristan chimed in.

"It was the pet of the original Salazar Slytherin himself. The founder of the clan. According to legend, it lived beneath Hogwarts Castle."

Harry blinked.

"Wait—wait, wait, wait. Time out. There was a giant death snake living under a school?"

Rosa raised an eyebrow.

"Magic school."

Harry slowly sat back, face blank.

"...I need tea. Or a nap. Possibly both."

Tristan chuckled.

"You'll get used to this. Or you won't. Either way—it's your legacy now."

Rosa tilted her head slightly, studying him.

"You're taking all of this... surprisingly well. Why is that?"

Harry opened his mouth as if to answer—then closed it. He looked down at his hands for a moment, quiet. Then, softly, almost like he was realizing it for the first time himself, he spoke:

"Because… I realized something."

He looked up, his green eyes calm but vulnerable.

"This means… I have a family."

Rosa smiled softly and reached out, gently patting Harry's messy black hair.

"Well then… we're your new family now. Come on, let's go meet the Clan."

Harry blinked, tilting his head.

"Oh great. Straight into the snake pit."

Tristan, who had just taken a sip of his coffee, choked and wheezed with laughter.

"That's exactly what I said the first time Ro—"

He was cut off by Rosa jabbing him hard in the ribs, eyes narrowing.

She turned to Harry, clearing her throat.

"...Accurate. Lord Slytherin might laugh at that."

She leaned in slightly, lowering her voice.

"Lady Slytherin, on the other hand? Don't say that around her unless you enjoy being turned into a toad."

To be continued

Hope people like this ch and give me power stones and enjoy