The Metamorph Next Door

This fic’s premise is inspired by the webtoon/pornhwa titled The Gacha Girl Next Door/이웃집 가챠걸  by malgwang and their artist hip . Please check them out.

Story Starts

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Ch. 0 Prologue -

The Room Overcrowding

Conundrum

Waifu of the Week: She-Who-Must-Not-Be-Called-By-Their-First-Name

Nymphadora Tonks!

Disclaimer: In this story, Hogwarts begins at age 12, so by the time they graduate from 7th year, they’d be at least 18, given that Voldemort destroyed Hogwarts. Harry Potter starts his Magical Masterals at age 20, Nymphadora (don’t call her that) is a bit older than him here.

~3rd Person POV~

Tonks, unlike most metamorphs—well, it’s a rare trait to begin with—didn’t learn about her metamorphing abilities until she entered puberty.

One morning, she woke up, her covers drenched, confused and her nether regions tingling pleasantly—her first orgasm, brought on by a wet dream.

A raunchy but pleasant dream she had, which involved the bassist of the band Weird Sisters, Jason, and their lead guitarist, Elaina—a dream I’d later describe as a fan sandwich, and one her mother banned outright from household conversation after catching her describing it to her friend Hestia.

The band—founded by the sisters Elaina, Fern, and Blair—was a sprawling twelve-member ensemble: a singer, two guitarists, a bassist, a keyboardist, three brass players, and a four-piece string quartet.

Rumour had it they were a coven, mainly comprised of witches with big personalities—putting it lightly—and just three wizards. After every show, they supposedly invited lucky fans to all-night, potion-fuelled orgies—an image Tonks figured had sparked that first wet dream

After cleaning up—trying to hide the fact that she’d wet the bed in her teens—Tonks took a shower and returned to find a stranger in her mirror. One who morphed back into her familiar reflection as the shock wore off. That’s how she discovered her gift—and started experimenting.

Her mother, Andromeda, found out soon after—walking in on what she thought was a stranger in her daughter's room. She assumed her daughter had sneaked one of her friends in. That illusion was quickly shattered when Tonks morphed back to normal.

“...!”

“Oh! I think your cock twitched. Did you like that?” Tonks murmured, pressing her body to Harry’s as she toyed with his nipples—popping one into her mouth mid-sentence, her tongue swirling against his areolas, weaving pleasure into her long-winded origin story.

“Uh…” she suddenly moaned—Harry’s cock still nestled inside her slick, hot folds. As Harry lay on the floor, he shifted to crack his neck, feeling a bit uncomfortable. The motion jostled his cock deeper inside her, sparking another ripple of pleasure up her spine.

“Hmmm… looks like you’re getting uncomfortable there.” She said teasingly as she moved forward, her face now parallel to Harry’s face as the heat of her breath grazed his face.

Her face melted into a blissful grin as she slowly pulled off him, a glistening trail of slick connecting their throbbing sexes. Harry’s cock rested against his stomach, flushed, and leaking precum.

Tonks dismounted and kneeled beside Harry, her feet underneath her shapely arse as she gave Harry’s cock a few tugs, inspecting it, her hands unable to wrap fully around the member.

“Wow, I can’t believe that this was inside me. Do you fucking have centaur blood in your family?” Tonks joked, her hand not leaving his hardness as Harry raised an eyebrow at her, giving her a deadpanned stare.

“Come on, let’s move this to the bed. I still haven’t finished my story.” Tonks said as she stood up, extending a hand at Harry—her breasts dangling, gently swaying from her earlier movements

“And I’m still nowhere near finishing.” Harry threw a sarcastic remark.

Harry made a face as he soon found out that the hand he reached for was the same hand on his cock seconds ago—still slick with juices. As Tonks helped him to his feet, he wiped his hand on her breast, smearing the mess across her skin—though not before giving it a firm squeeze and a cheeky tug at her nipple.

“Touché. Now lie down,” Tonks said, pushing Harry onto his back. She crawled over him from the foot of the bed and rose to her knees, his hands settling on her thighs, thumbs drawing slow circles. Reaching behind herself, she guided his cock back into her slick, heated core.

A pleasured squeal escaped her as Harry—feeling himself slide into his pink-and-purple-haired senior—tightened his grip on her thighs and bucked his hips, thrusting deep into her.

She felt the tip of his cock kiss the entrance to her womb as her walls rippled around him, clenching with every pump. She tapped at his chest. “Harry… Wait. Wait Wait..uhm.. Still… not ready!” she gasped, her words spilling out between each thrust.

With a sigh, Harry gave in, slowing his thrusts to a halt. Tonks leaned back, panting, her hand braced on his thighs for support.

“Fine, one pump chump,” Harry muttered under his breath—loud enough for Tonks to hear.

“Hey, I heard that—”

“That was the point,” Harry cut in.

“I’m just extra sensitive for some reason. I was flicking the bean for hours without a single release—then you show up with that lewd magic wand of yours, and boom. Instant cum al ye faithful.” Tonks leaned forward, pressing her chest to his, her quick heartbeat thumping against his skin.

“Give me like ten to fifteen minutes, and I’ll take care of you.” She said panting—still joined with him, their bodies intimately connected

“Hmmm… Fine.”

Tonks grinned as her voice turned playful as she rested the side of her face on Harry’s chest. With a cheeky flick to his nipple, she added, “Now, where was I?”

The motion elicited another soft moan as his cock twitched inside her in response.

Then Tonks explained how, over time, her control over her ability began to flicker—not constantly, but enough to be annoying. Some days she’d manage perfectly fine, while on others, parts of her form would shift without warning.

It wasn’t until a eureka moment after another wet dream that she finally connected the dots: her metamorphing faltered whenever she was sexually frustrated.

The solution had once been simple: regular masturbation sessions—or, as she put it with a grin, ‘flicking the bean.’ Charming or disgusting, really, depending on whether you are a glass-half-full or half-empty type of person.

And for years, that worked just fine. She even had some satisfying lovers during her Hogwarts years. But as time went on, orgasms alone weren’t enough—she needed to feel truly satisfied.

Without satisfaction, her form would lock up—leaving her stuck in a random form until she relieved the tension. Which led to the scene just a few minutes ago—Tonks, trapped in a haze of lust, unable to find release.

Typically, this wouldn’t pose a problem—she could stay in a single form for days. But when duty called, whether it was something official, like going to Gringotts, or just her part-time job, it turned into a real headache.

Even her past lovers hadn’t been up to par—at least not in the way she needed.

“That’s why I have a proposal for you,” Tonks said as she sat upright, tucking her legs beneath her and hooking both her feet into Harry’s inner thighs.

Bracing her hands on his stomach, she lifted herself, then dropped down, impaling herself fully on his length.

“Fancy being my go-to shag partner? We can call it friends with benefits if that’s easier on your de–li–cate sensibilities,” she offered brightly, dragging the word out as she rocked her hips back and forth.

Harry just quirked an eyebrow at her—half amused, half incredulous at her phrasing.

“While I did say I don’t mind being stuck in another form, it’d be so much more convenient if I could actually control it. Mum referred me to a specialist—we’re working on Occlumency exercises now. Apparently, it’s more of a mental thing than a weird quirk of my ability.”

She pitched forward, her tongue gliding up Harry’s chest before she suckled at his neck, drawing a shiver from him. She trailed kisses across his collarbone, then nibbled at his earlobe.

“What say you, Mr. Potter?” she whispered into my ear—soft and sultry. “In exchange for satisfying me whenever I need it, you get a fun, cute, sexy, me–ta–morph at your beck and call… with everything that goes with it.”

As she emphasised each syllable, her fingers danced across his chest.

Harry snorted, folded his legs, bucking up—thrusting hard into the coy nymph perched above him.

“Are you sure about this? I do have a lot of pent-up frustrations. I mean—you’ve probably heard about my situation. From your dad? Ted’s your father, right?”

With only her knees touching the bed, each of Harry’s thrusts made Tonks feel momentarily weightless—her whole body lifted with every plunge.

“Uh—” she gasped, her moan hot in his ear, driving something primal in him. “F–uck. First: yes, he is my father—and fu–ck, please do not ever bring him up mid sex.

“And as for your first question—” Tonks leaned over him, their lips nearly brushing.

“My safe word is Toucan… and break me, baby!” she challenged, then closed the distance—kissing him deeply as she cradled his face, while Harry, hands gripping her waist, kept pounding into her slick, eager heat.

Tonks broke the kiss first, gasping for air. Her moans didn’t stop—she squealed and mewled, eyes shut tight, one hand squeezing her tits as she bit her lip in pleasure.

Harry pulled on her waist, driving into her balls-deep. Her hips jolted with every thrust, lifting her off the bed. The rhythmic slap of flesh on flesh filled the room, and the smell of sex and sweat permeated thickly into the air.

Still not close to coming, Harry withdrew abruptly. Tonks let out a begging moan at the sudden emptiness—just before he tipped her onto her side.

Rising up, Harry repositioned himself behind Tonks, cock in hand, guiding the head against her soaked fold as he searched for her entrance. And upon finding her heat, he plunged in deep, hooking her right leg with his arm—the same arm hand grabbing at her tit, squeezing hard. His left foot pinned her lower leg in place as he began to thrust with a relentless pace.

“Yes, Harry—uh right there, fuck that pussy,” she groaned, leaning back into him. Her right hand tangled in his hair, tugging, playing, while her other hand rubbed furiously at her aching clit, desperate for more attention.

Harry—continuing his onslaught—leaned forward, nose at the back of her head, inhaling her scent—a heady note of nutty coconut—before nibbling the top of her ear.

“Please—I’m close.” Tonks gasped, voice sultry and breathless as she matched him thrust for thrust, fingers still circling her clit. Slickness flew between them, coating their thighs, the slapping sounds relentless in their haze of lust.

With a deep thrust, Tonks buckled—screaming as she came. Her walls clamped down hard around Harry’s cock, her mind short-circuiting from the pleasure, body jerking as she began hiccuping uncontrollably.

Harry, still rock-hard and unsatisfied, pulled out. He circled the hiccuping, twitching mess of a witch, low lying prone with both hands at her sides.

Kneeling between her legs, he grabbed at her waist and pulled her up.

“Harry—please wait—”

“What, another ten to fifteen minutes?” he shot back dryly.

He ignored her plea, spreading her legs with his knees, tilting her hips just right—his cock brushing against her soaked entrance.

“Ready?” Harry asked.

Bracing herself on her elbows, Tonks just muttered, “Fuck it.”

Just like before, there was nothing tender in his approach. He slammed into her again, her arse rippling with every thrust, cheeks slapping hard against his waist.

Tonks, lost in a daze, bit down on her knuckles—orgasm after orgasm crashing through her. The hiccups made everything more intense, annoyingly inconvenient and yet weirdly erotic.

Harry reached forward and grabbed both her wrists, pulling her torso up as he leaned back. Her head lolled, breasts bouncing wildly, arms stretched taut while Harry held her, thrusting faster and harder.

Slick juices overflowed, streaming down her thighs as the relentless pounding continued—time all but forgotten. Tonks was a moaning, breathless mess as Harry chased his own climax.

“Where?” Harry asked, snapping her from her haze.

“Any—uh–where–on pot–aghhhhhhn!”

With one final thrust, Harry Potter emptied himself into the metamorph, filling her womb with thick spurts of cum. He stayed deep, panting, bathing in the aftermath of their shared high.

Gently releasing her wrists, he eased her back into the bed, letting her collapse in her spent, hiccuping state.

Feeling a twinge of guilt at the mess he’d made of her, Harry trailed kisses up Tonks’ back, then lay down beside her, arms behind his head. She shifted with a groan and laid her head on his chest, their scent intertwined, their chests somehow rising and falling at the same time.

“So…” Harry said, teasingly, “how long before you’re up for another round?”

Tonks lazily lifted one hand and gave his chest a weak smack.

“Hic—Toucan,” she muttered, before drifting into sleep.

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END

Waifu of the Week: Base Nymphadora Tonks

*Waifu of the week - Again, this fic is inspired by The Gacha Girl Next Door, where Tonks morphs into a random form; she’s unable to control her Metamorphmagus abilities unless she experiences the satisfaction.

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