This chapter contains smut!
Harry shifted in bed a little, his cock rock hard. It had barely been five minutes since he and Nym had laid down together, and he had had to keep shifting at least ten times.
The problem was that Nym's large tits pressed up against Harry's back was keeping him very hard, and she was spooning him, so he couldn't exactly move, not that he would want to.
"Harry… why do you keep moving around?" Nym whispered in Harry's ear, sending a shiver down his spine. The older girl pressed herself tighter against Harry, and she rested her chin on his shoulder.
He heard her mutter something, and then she gave a gasp.
"Am I getting you all hard?" Nym teased. Harry startled.
"What? How did- no!" Harry tried. Nym laughed and rubbed her tits against his back playfully.
"You like your big sister's big titties?" Nym purred.
Harry groaned as Nym's hand, which was sitting around his stomach, slid downwards until she cupped his bulge.
Harry's hips bucked violently.
"Damn, Harry. You're big down there, especially for a guy your age." Nym said in surprise.
"You were having sex in your second year?" Harry grunted as Nym started rubbing Harry's bulge.
"No, I lost my virginity fourth year, to a guy less endowed than this." Nym said.
Nym whispered something again, and Harry felt a peculiar feeling in his brain, like a gentle breeze inside.
"You're thinking about fucking me, huh?" Nym murmured in a husky sort of voice.
"Nym, are you reading my mind?" Harry exclaimed.
"Mm hm." Nym said, and kissed the side of Harry's neck, "The dirty perverted things you're thinking about doing to me… it's all rather stimulating."
Oh, Merlin. This was embarrassing.
"You know, Harry… I wouldn't mind giving you a birthday present you'd never forget…" Nym said suggestively. Harry whipped around to stare at the purple haired girl he basically considered to be his elder sister.
"What?" Harry asked in astonishment. Nym smiled at him.
"I've seen your thoughts, Harry. I know how much you want me." Nym whispered, "And I'm always down to help my little brother out."
Harry stared as Nym grabbed the hem of the shirt she wore (his shirt), and pulled it off, unveiling her turquoise bra.
Harry reached up and grabbed Nym's tits, squeezing them without remorse. She let out a soft sigh, before reaching around and unhooking her bra.
Harry took his hands off of Nym's bra, and it fell onto the bed between them.
Harry looked down at Nym's lovely breasts, and then, to his amazement, they swelled up before his very eyes, growing to an incredibly large size, so busty that she outweighed her mother now.
"Nym… holy shit." Harry gasped. She smirked at him.
"I saw that you were definitely a tits guy." Nym winked. Harry attacked Nym's new superlarge tits, amazed at how pillowy and soft they were. At first he was just groping them, but that wasn't enough. He leaned down and kissed the tops of her melons, then trailed kisses down the large mammaries to her nipples.
He silently thanked Cassandra's tutelage as he swirled his tongue closely around the nipple, then went in wider and wider circles to pleasure the entire areola.
Nym let out a loud gasp at Harry's skill with his tongue on her breast. His hand was lifted to grope her other breast while he pleasured her left tit.
"Oh, Morgana!" Nym cried, "How are you so good at this?"
"I'm just a natural." Harry said smugly, then took her nipple into his mouth, tugging it. Nym sucked in a breath, and Harry bit down gently on her breast.
Nym whimpered, and Harry was amazed at how sexy that sound was. Nym wrapped her arms tightly around Harry, pulling his face properly into her bust. The full pillows of her breasts engulfed him, and he enjoyed just how large she had made her tits.
Nym tugged at Harry's shirt, and he regrettably had to pull his face out of her heavenly pillows in order for her to get his shirt off.
Nym slid into Harry's lap, and he enjoyed her round ass on his rock hard dick.
"You really love big sister's tits, huh?" she teased, cupping Harry's cheek.
"They're fucking amazing." Harry said unabashedly. Nym smiled.
"They're too big for day to day life, so you're only going to get puppies like these in bed with me." Nym told him.
"I'm perfectly fine with that. Can they go bigger?" Harry asked eagerly. Nym's full lips curved into a smile.
"Boys always want more, huh?" Nym said playfully.
"Is that a yes?" Harry asked. Nym leaned back a bit so Harry could see her breasts, and she closed her eyes tightly. Harry watched in fascination as her tits grew more and more.
By time she finished, each breast was the size of a globe. Like, literally the size of a globe.
"Holy hell, Nym." Harry said, running his hands across her globe-sized breasts, squeezing as he went.
"Yeah, you can see why I don't walk around with these all the time. This is my maximum breast size. I've tried before, just to see how big they could go, but this is the biggest. They're heavy as fuck." Nym said, and Harry laughed.
"I'm sure they are! You have two fucking globes on your chest." Harry said, astonished at Nym's abilities.
"I have to strengthen my spine just so I don't fall over, but you can't see how much I have to reinforce myself so these don't break me in half." Nym joked, cupping one of her obscenely large breasts.
Harry leaned down and licked across one of her enormous breasts.
"Mmm… that's the spot, Harry." Nym said happily.
She looked at him curiously.
"You want to see what else I can do?" Nym whispered. Harry nodded.
Nym stripped off her panties, and Harry got one look at her pussy before her body shifted. Her globes shrank down to more normal sized breasts, though still quite large by Muggle standards. Her skin lightened from a golden tan to a creamy white. Her long straight purple hair faded into golden waves, her eyes turned piercing blue, her facial features rippled and her body curved in new ways.
Nym sat up, grinning, and Harry was stunned.
"You're… Daphne." Harry realized.
"Yeah. I'm Daphne as she would look at my age." Nym said, even speaking with Daphne's voice. Then, her body rippled again and Harry was looking at present day Daphne. Her breasts were smaller and her curves less dramatic.
"Was that… an accurate representation of how she'll look?" Harry asked, his rock hard cock throbbing. Sure, he'd always known Daphne was gorgeous, but they were just friends. He knew she didn't really want to marry him. But now… Harry wasn't sure he wanted to just be friends with Daphne Greengrass, looking at how hot she was naked.
"I don't… change." Harry said, his thoughts confusing him.
Nym nodded. She changed back into herself, with her usual large breasts, not the insane globes.
"Alright, enough playing around, huh?" Nym asked, looking down. His cock was straining against his pajama bottoms.
"I could be convinced." Harry said, and Nym smiled.
She grabbed her wand, and with a quick charm, Harry's clothes turned to air, vanishing.
"Whoa." Harry said in surprise. But Nym was hardly listening. Her eyes were firmly on Harry's cock. It had grown a bit since his Christmastime sex with Cassandra, but wizards didn't really flourish into physical maturity until they were fifteen or so.
"You've got quite a wand there, Harry." Nym said playfully, reaching down to wrap her hand around it. Her hands were extremely soft, and Harry groaned as his 'big sister' gave him an amazing handjob.
"Nym…" Harry gasped.
"Enjoying yourself?" Nym teased. She leaned over, and kissed him. Harry and Nym's tongues collided while she kept rubbing his cock, her thumb brushing across his sensitive tip.
Harry reveled in both Nym's lips and Nym's hand, and he felt an explosion building.
"I'm gonna…" Harry groaned, and Nym gave a hum of approval, her hand moving swifter.
Harry couldn't hold back any longer, and his cock twitched before spurts of his white seed shot up onto Nym's stomach, sliding down to her pussy.
"Mm… let me get my wand and you can fuck me, sound good?" Nym asked, and she planted a quick kiss on Harry's lips. Nym leaned past him, her hard nipples brushing Harry's chest as she grabbed her wand, and then she pointed it at her pussy.
She spoke the contraceptive charm clearly, and then she tossed her wand aside onto Harry's nightstand, where it rolled until it hit Harry's wand, the two wands lying side by side.
Nym tossed back her violet hair and then she placed her hands on Harry's shoulders, lifting herself up until her entrance was right above Harry's cock, which still glistened with pre-cum.
Harry expected Nym to go down inch by inch, but to his amazement she just… dropped.
Harry and Nym both let out loud sounds of pleasure as Harry's dick was abruptly buried inside her tight pussy. In fact… was it getting tighter around Harry's cock.
Nym started bouncing on Harry's cock, and each bounce of hers made Harry's cock shove through Nym's tight walls, which abruptly tightened again after each bounce.
"Nym… are you… tightening…" Harry groaned.
"Yes!" Nym gasped breathlessly.
Harry put his hands on Nym's hips as she bounced up and down on his cock, driving him half mad with lust.
Harry grunted and without warning Nym, he exploded cum deep inside her.
Nym let out a throaty purr of happiness.
"Attaboy." Nym moaned, throwing her arms around Harry and clinging to him while Harry kept cumming.
"You didn't… you didn't orgasm." Harry said weakly.
"Baby brother, I can turn my pussy into an inward facing dick and fuck myself silly any time I want. Metamorphmagi have incredible stamina, and I'd probably kill you at this age if we went until I orgasmed." Nym explained, which made Harry feel a bit better, but still a bit disappointed.
Nym leaned in and gave Harry a long, loving kiss.
"Don't worry. I'll let you keep trying as much as you want. But for right now, I think you need some rest. You have a lot of presents to open tomorrow." Nym smiled.
"Can you… can you make your tits huge again?" Harry asked. Nym kissed him again, and her tits swelled up against his chest back to globe-size.
Nym rose up off of Harry's cock and laid down on the bed. Harry climbed on top of her, his still half-hard cock sliding inside her. Harry laid his head on one of her globe sized breasts, and it made an excellent pillow.
Nym stroked along his back lightly, and the exhausted birthday boy fell asleep.
———
Outside the door, Lily Evans drew away, stunned. Her pussy was insanely wet, and her thoughts were occupied by what she had just witnessed.
After hearing strange noises coming from Harry's room, she'd gone to investigate, only to find him fucking Tonks.
For some reason, she had stayed and watched, her eyes firmly on her young son, and specifically his cock whenever it wasn't sheathed inside his pseudo-sister's pussy, and each glimpse of it got her pussy wetter.
She hated herself for it, but she could not deny the truth:
She was aroused by the sight of her own son's cock.