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Grown to be

Summary:

An accident in Potions class has lead to the de-aging of Regulus Black, and you know how bad kids are at keeping secrets, even their own.

 

or

 

The longest build up ever for a single kiss.

Notes:

Can you spot the easter eggs/movie references?

Work Text:

Why is everyone so mad? He didn’t like it when people is mad. Mad meant Mother punish Siri. 

“Oh dear… and how much leach juice you said you used, Mr. Crouch?” 

“I swear Professor Slughorn! One dash of leach juice and one dash of cowbane.”

“And we stirred real good!” Regulus cried. “Please don’t punish Barty! He’s my bestest friend!” His nose started itching with unwanted tears.

“Oh dear…” Professor Slughorn repeated for the millionth time. “Class dismissed. We’ll test the rest of the shrinking potions tomorrow.” His classmates started bottling the potions while looking at him real funny. He wanted to cry. And kick them. He didn’t like it when people stared at him. “Given the current events” Slughorn spoke to the students again “it will be best if you bring your familiar with you to finish the assignment. “Mr. Avery go fetch the headmaster, Mr. Crouch you go get Mr. Black’s brother.” 

***

“It’s not even the fact that he's my brother, mate, it’s just that he’s a year below us!! Nobody dates below their year, that’s disgusting.” Sirius barked walking down the classroom corridor.

It had been ages since they had caught on to the fact that James was pinning after his little brother and he couldn’t be less pleased about it. Regulus never cared that much for James but his opinion on him turned into straight disgust the moment Sirius ran away with the Potters. And Regulus was not shy about it either. On a good day, Regulus would only pretend that James didn’t exist. 

Yet, somehow, the four-eyed bellend had fallen for him, and it was starting to affect all of them. At first it was just silly stuff like James’ grades going down – who cared about those?- but now Gryffindor had lost their last Quidditch match, and that was serious business. 

“Does that mean you wouldn’t date me if I was a fifth year?” Remus dared to ask.

“What? No! That’s different!!! You’re… you. You’re Remus! Completely different!!!!” Sirius sputtered nervously. “It’s just that fifth years are literal babies, what do you even do with them??”

“Our beaters are fourth years…” James muttered defeated.

“Yeah but that’s also different! That’s Quidditch!!!” Sirius insisted, confused as to why nobody seemed to be on his side.

“Are you sure this is not about the fact that James fancies your brother?”

“No, of course not. If anything, incest aligns with the family traditions. Well done keeping the blood pure, Prongs.” James glared at him, but it was true. He wasn’t ecstatic about Reggie dating in general, he was just a baby. But if it had to be, one day in the very far away future, when Reggie turned 30 and was proper ancient or so, James seemed a much safer choice than any of the good-for-nothing Slytherins Regulus surrounded himself with.

“Well it’s not like it matters really.” Peter added. “It’s been months of this and Regulus doesn’t even look in James' direction.” Their friend made a disgruntled noise. “I’m telling you mate, we all know the bloke despises you, just get back with Evans.”

“Wormtail, I'm not going back with Lily just for the sake of it.”

“Not that she would take you back either.” Remus cackled. 

“Well if you insist on this ridiculous celibacy thing then at least you could jerk yourself off in the loo, you're making the dorm reek like jizz.” Pete complained. 

“Fat chance, I can see that picture of your mum on your nightstand from my bed.”

They all started cackling as Peter clutched his stomach, retching noises still filling the corridor when a Slytherin kid from Reggie’s year came running towards them.

“Sirius?” The Slytherin struggled for air. 

“Yeah?”

“You gotta come with me. Professor Slughorn orders.”

“Oiiii you heard that lads, old Sluggy trying to get me to join his club again”

“No!” The Slytherin croaked. “It’s erm… it’s Regulus… we errr Slughorn had us brewing a shrinking solution and…”

“And…”

“I don’t know mate, I swear we didn’t use that much leech juice, but Slughorn's antidote it’s not working and now he’s stuck.”

Sirius bolt in the dungeons direction before the Slytherin could blurt another word out.

***

“No!” Regulus protested, stomping his feet.

“Mr Black…”

“I don’t wanna!!!” 

“Reggie, Professor McGonagall is already doing us a solid here.”

“No! You smell!!”

“Bloody…” Sirius inhaled deeply, trying to fill himself with air and patience. Regulus had gotten stuck in the body of a toddler and send him to St. Mungo’s would mean send him to their Mother and despite their less than cordial current relationship, he couldn’t do that to his baby brother. “Reggie, it’s either me taking care of you until Slughorn brews a different antidote or Mother is going to take care of this”

Regulus recoiled, making himself smaller.

“No…” He whimpered in that tiny voice of his. “I don’t wanna go with Mother.” 

“C’mon then.” Sirius said, offering his hand. “We used to have fun didn’t we?”

“Yeh…” Reggie cried again, so small you could barely hear him.

“I have sugar quills in my trunk y’know?”

Regulus' eyes widened with childish hope. “Green ones?” He asked.

“Pffft of course green ones!” Sirius replied with exaggerated disbelief. 

“Yay!” Regulus grabbed Sirius’ hand with a cheer that almost made him forget about the way he had just retracted himself at the mention of their mother.

“Yellows are yucky you know?”

“Yeah I remember,” Sirius agreed with a soft laugh.

***

“Lads? I'm calling off all pranks for the foreseeable future. Reggie’s fine, mostly, and Mcgonagall is being a true one and she’s letting him stay with me instead of calling home.” Sirius announced entering the Gryffindor common room where Peter and Remus seemed to have lodged themselves waiting for his return. “Perks of being of age, lads. Minny says I’m a full adult.”

“Do keep telling yourself that.” Remus poked perking up. “Wait, he’s a toddler?”

“Oh my god he’s truly tiny.” Peter marvelled. “HELLO REGULUS I AM PE-TER CAN YOU SAY PE-TER?” Peter asked, enunciating slow and loud. Regulus looked a mix between pissed and unimpressed.

“Your friends are stupid.” He told Sirius to the loud amusement of Remus.

“Oh Merlin, I'm already loving this.” Remus said with amusement. “So how does this work again?”

“Apparently they were studying the Shrinking Solution and Reggie and his potion partner, that Crouch kid, they added way too much cowbane.”

“I DID NOT” Regulus cried trying unsuccessfully to interrupt. 

“So now the regular antidote doesn’t work on him and he’s stuck like this until the old Sluggy finds a solution.”

“Why didn’t they use toads like we did last year?” Peter asked. 

“Apparently Slughorn didn't want anyone repeating the same mayhem we made.

“Woops.”

“So is he like a regular toddler or…”

“I’m Regulus, not regular!” 

“Well…” Sirius replied, trying to hold a proud grin. “I mean, he’s just shrunk. So he's just him, but with the social skills of a… 5 year old? Maybe 4?”

“Brain development.”

“Same thing.”

“And you agreed to stay with us?” Remus asked Regulus.

“Siri said he’s giving me sugar quills.” He said very sternly.

“Siri…” Mocked Remus. 

“Not yellow ones.” Sirius agreed, barely containing a smile. “Those are yucky.”

“Mate, they’re sheer sugar, they all taste the same.” Peter added.

“NUH HUH” Regulus argued, puffing his tiny chest. “Yellows are yucky!!!!”

“Yeah Peter.” Remus mused. “Yellows are yucky, how dare you.” This was obviously way too amusing for him. 

It was then when the portrait hole opened again.

“Pads, what the hell? I’ve been waiting for you in the infirmary! You could’ve sent a patronus or something!” It was when James finished entering the common room that Regulus hid behind his big brother's legs. Clutching so hard to his uniform that he was seconds away from mooning the common room.

“Oi oi Reggie!” Sirius complained, pulling his trousers up. “What are you doing? What's gotten into you? It’s just James!” He asked, turning his body towards Regulus. But his baby brother just buried his face again followed by tiny fists punching his body as hard as they could.

“SHUSH!!!!” He cried with his voice all muffled by Sirius’ legs.

“Is that Reggie?” But the only answer was a painful sob before silent tears started wetting Sirius trousers.

“Hey hey hey it’s just Prongs what’s wrong? You know Prongs!”

“Did I startle him?” James frowned.

Sirius picked the silently sobbing Regulus and hoisted him on his left hip, but he quickly hid his face again on the crook of Sirius’ neck.

“Well, at least I’m not the one he dislikes the most.” Peter announced. “Some things never change.”

“What did I even do?”

“Shhhhhh” Sirius shushed against Regulus' curls. Kissing his hair and rubbing his back in a soothing motion. “I’m here, Reggie. You want to go grab your quills now?” But Reggie was frozen. Face buried away and white knuckles grabbing Sirius clothing. “Ok, let’s get your non-yucky sugar quills.”

“Is there anything I can do?” James offered with a tinge of helplessness to his voice.

“Nah, it’s all good. I think he’s just got a bit shy.” As soon as he said the word shy, Regulus' hand unfroze and started relentlessly hitting Sirius' chest, much to the amusement of the older Black.

“Merlin.” James muttered. “Sirius never mentioned Regulus being such a mousy Pygmy Puff when he was little.”

“Mousy, my arse.” Peter replied. “Tiny twat just called me an idiot!”

***

“Well, Reggie. You don't want to sleep in my dorm, you don't want me to ask McGonagall for private quarters and you can't sleep on your own dorms by yourself in this state. So far so good the only thing we agree on is that my head is fat, and I'm still not sure if I'm on board with that one.” Sirius tried to reason with his brother.

“I wanna go to my room, cause I'm fifteen and I’m fifteen so I don't want to sleep with you and I don't need a babysitter cause I'm big.” Reggie said very seriously with a frown in his face. He was so fucking adorable that it was hard not to smother him with kisses.

“Hiya.” James said entering the dorm. “McGonagall said it was fine if you both skipped lunch today, but I think the elves went a bit overboard.” His arms were filled with pumpkin pasties, sausage cauldrons and frosted cookies too. “I could definitely use some help eating all of this.” He said with a careful smile.

Regulus, who was already kicking the bedding down to hide, felt called out enough that he stretched out an open hand towards James while still refusing his eyes. 

“Why thank you little prince, that’s very kind of you.” James mused once again, placing a sausage cauldron on Reggie’s hand and throwing a pumpkin pastie against Sirius’ face. 

It made the wrong Black brother laugh. 

***

According to Sirius calculations it took less than two days for every girl in Gryffindor tower to coo all over his baby brother. 

What a waste. 

At least Reggie was so busy being annoyed at the attention that he forgot all about those weird bouts of shyness he was getting around his friends. 

“Oi Moony.” He whispered over his baby brother's head. “I feel a bit overwhelmed here. Let’s go upstairs and make out for a bit.” 

At this, Regulus snapped his head around so quickly that Sirius feared for a second it would do a full cauldron spin. 

“I heard that!” He snapped in that high-pitched child voice.

“So?” 

“You can't have a boyfriend!” 

“Says who?”

“Says Mother!” 

“I don’t care what Mother says.” Sirius snorted. 

“That’s not fair!” Regulus snapped, jumping down from the sofa and stomping his foot. “Not fair! Not fair!”

“What the hell?” Sirius said in shock, the whole common room was starting to pay even more attention to them. “What do you even care? I’m not even the heir anymore, you are!” 

“Not fair!” Regulus cried again. “If you have a boyfriend I want one too!” 

“Well fucking suit yourself! What are you on about?” Sirius asked, more confused by the minute.

But Regulus was a kid on a mission. He started frantically looking around, looking for what, Sirius didn’t know, but once he found it he jumped into action. 

“You are my boyfriend now.” 

***

James, who was in the middle of a chess game against Lily, stopped to watch the row between the Black brothers. They had had several of these already and it was immensely amusing to watch Sirius measure up to a five year old. It made him ache for the siblings he had never had. 

“Doesn’t this make you miss your sister?” 

“I told you before, Potter. You romanticise the idea of siblings a bit too much.”

Lily started explaining again how much her sister despised her, when something knocked the air out of his lungs. 

“You are my boyfriend now.”

“Uh… What the fuck is going on?” James lifted his hands in the air when Regulus started gripping his middle. 

“If Siri has a boyfriend, me too.”

“Wow Potter. This is not the way to get over me y’know?”

“That’s not funny, Lils.” He scolded much to her amusement. “Pads! PADS!” 

“No, Reggie!” Sirius approached them. “I didn’t mean you can call anyone your boyfriend.” 

“He’s mine!” Reggie screeched again. “You have YOUR boyfriend. This is mine!” 

“You have to get someone you like Reggie!” 

“Pads, I’m quite sure that’s not the fucking issue here.” James complained with his hands still up.

“Reggie let go!” 

“No! He’s mine!” 

“Reggie, let go of Prongs.” 

“No! I want James! He’s mine! Mine boyfriend!” 

***

“Well… look at the bright side, Regulus is finally paying attention to you.”

“Not cool, Peter.”

After a good tantrum and a solid cry trying to cling on to James, Regulus had fallen asleep in the Gryffindor Common Room, then woke up again as Sirius carried him up the stairs to the dorm and then had another tantrum cause he insisted he wanted to sleep with James in his bed. They were all now surrounding said bed, staring at Regulus, who was now sleeping like he didn’t have a care in the world, splayed and occupying as much of the bed as his tiny frame allowed him. 

“Well,” James continued. “I guess there’s only one thing to do.” 

“Yeah,” Replied Sirius, staring sternly at his brother. “Kill you.” 

“What?” James snapped his face to Sirius so fast his neck actually did a crking noise. “No! What do you mean kill me? What did I even do? I meant you sleep with Moony and I take your bed!” 

“Sorry mate, that’s how it works.” Sirius nodded, like he had made his mind. “You groomed my baby brother, so now I have to kill you.”

“PADS!” James screeched, opening his arms in disbelief. “How the fuck did I groom your brother?”

Remus and Peter were starting to giggle and chuckle at their antics, but James found nothing amusing at the current situation. 

“Are you gonna look me in the eye and tell me you haven’t been pining over him for the last few months?” 

“Fifteen Sirius!!! When he was fifteen!!!! Not as your fucking toddler brother!” 

Regulus stirred, as if all the yelling had finally got to him. They all froze. 

“There’s no difference!” Sirius whispered-yelled. “He was a baby just the same, now look what you’ve done!” 

“It’s a ten year old difference you twat!” James whispered-yelled back.

“Ok lads.” Remus interrupted, stirring Sirius to his bed, leaving a free bed for James just as he had suggested... “How about we all go to bed and leave the killing for tomorrow?”

“I still think I should kill him, Moony.” 

"Well I think you should kiss my actual hole, Padfoot."

“And I think that’s a great idea, my star." Remus coddled, ignoring James. "How about we plan how to get rid of the body first?” 

“Hmmmm that actually sounds fair, Moony.” 

James let out a humf of disbelief as they closed the drapes to their bed. 

***

The next morning, James woke up with a stabbing pain on his side. When he, much to his distaste, woke up, he found a small but filled with dishevelled curls head staring at him from the edge of his bed. Sirius’ bed. An equally tiny finger dragging back over the matters from where he had been stabbing James.

“You leaved.” Regulus said with accusatory gray eyes. 

“Regulus, the sun is barely out, what are you doing? Go back to your bed.”

“No!” He protested, stomping his foot. “You’re my boyfriend I wanna sleep with you! You said you liked me!” 

“I— What?” 

“Oh you’re fucking dead meat, Potter” Sirius suddenly barked as he transformed into a very intimidating black dog.

***

“Is that… James, is that a bite?” Lily asked worriedly, staring at the bite on James’ arm. 

James, barely there, exhausted from the situation and the impromptu morning pyjama-run let his head drop with an empty noise onto the breakfast table. 

“I seriously think you should get that check, it doesn't look good, James.”

“It doesn’t.” James smiled at Lily maniacally, Sirius said a scar would make a nice reminder and James wasn’t sure if he was joking, and given the circumstances he didn’t feel too much like finding out.

“Siri bitted James coz he likes me so much now and not you, cos he’s my boyfriend now!” Regulus announced with his mouth filled with Weetabix.

“What?! What do you mean he...? James! He's just a baby!!” 

“Oh for fuck sake.” James groaned once again.

***

“I mean you gotta give it to me, it’s a bit funny.” 

“Remus, mate.” 

James found nothing funny about the situation. Regulus had gone from hating him, to not being able to talk to him, to be obsessed with him in less than a week. With the bonus that Sirius had tried to kill him at least four times now.

“You know the worst part about it?” James mumbled exhausted. 

“Hm?”

“I miss him, Moony. I miss Regulus so much.” 

It was true, Regulus, his Regulus had vanished. The Regulus who flew every day at dusk until the stars shone bright in the sky. The Regulus from the Sphinx club who was skilled with his wand and sharp with his tongue. The Regulus that every morning entered the Great Hall with poise, walking with such strides that made the white shirt of his uniform cling to his beautiful clavicles. 

All he had now was a toddler and that wasn’t Regulus. And he was reminded of it every time he talked, because the toddler kept chanting his toddler obsession for James and Regulus Black, his Regulus, would never do that. Cause everyone knew, Regulus hated James. 

“I have good news then. That’s why I came looking for you. Slughorn did it. They’re about to try the altered solution now. Care to come with me?”

***

Regulus' whole body hurt as if he had swallowed a whole batch of Skele-Gro. He tried to breathe in and breathe out, letting the stinging sensation on his lungs to wake up his senses. In a sense, he guessed he had indeed re-grown all the bones and organs on his body but he didn’t remember the shrinking to be this painful. 

If that had only been the only thing he wasn’t able to remember…

He perfectly remembered that other night in the Gryffindor common room, and the outrage filling his body when he found out Sirius was out of the closet.

He had always known that Sirius wasn’t straight. He loved to be loved a bit too much, so of course his sexuality had come out as the one that allows you to be loved by everyone. What a whore of a soul he had. Thank goodness Lupin seemed to be able to put some sort of control on that one. 

But being out and open about it? Why did Sirius get to have that too? How was that fair? What was let for Regulus?

His brother already had a happy life, a future that belonged only to himself, the popularity, the looks and what hurt the most... he had James. So no, Regulus wasn’t about to let that one pass too. Enough had been enough. And if Sirius was free to love whoever he wanted, so was Regulus. 

James. Lovely James. 

James, who not only had stolen his brother, but had also stolen his heart with his bright smile that first day of September of 1971, while everyone else kept boarding the Hogwarts express as if the sun itself hadn't just punched the air out of his lungs.

James. Sweet and lovely James. 

He could still remember the face James had made when he told him he wanted him as his boyfriend.

He told him he wanted him as his boyfriend.

He told him.

Fuck.

***

“C’mon Regulus! The moon is out already! Come down!”

The pitch was so quiet that he could hear Barty calling for him even as he flew around the highest of the stands. He had been ignoring him since he found him on the pitch. 

The moment he got his sense back and everything he had done and confessed during those last few days downed on him, he ran away. He ran from Slughorn and his brother as if he was trying to leave behind all the mistakes he had made while his judgement was subpar at best.

It wasn’t his fault that Barty had found him so quickly. Because of course he did, who else knew him that well that knew to check the Quidditch pitch first even this late at night? What an annoying sod, trying to interrupt his plans of freezing himself to death by method of flying broomstick.

“Reg, c’mon! I’m cold! It’s not that bad! I’m sure Potter thought it was only toddler babble!!” 

Reggie couldn’t even stand the thought of it, he aimed his broomstick up, trying to get away from the voice and his friend’s empty promises about Potter not knowing. 

If he ignored it long enough it would disappear. 

Surely. 

Regulus kept flying up until his head started to get dizzy and the old school broomstick started to tremble from the height. Maybe it was the lack of oxygen or maybe he was finally going delirious, but from the wisps of clouds surrounding him came a voice who was like a siren call to him. 

“Reg? I can’t see you, Reg.”

He had done it, he had choked himself on the clouds, was dying and the other world was coming to get him. 

“I’m here.” He told the, oh so familiar and lovely voice, aiming his broom towards it, closing his eyes and letting the cold and wet air lick his skin as he broke through the mist. “Are you an angel coming to get me?” He asked, his head still spinning from the altitude.

The voice chuckled, and what a lovely way to go was to do it while hearing James Potter’s laugh. He must’ve not been an utter disgrace after all if the hereafter was welcoming him like that.

“I’m not an angel, Reggie.” 

“Then what a lovely fiend you make.” He replied back without missing a bit. 

His broom was gently stopped, the fiend had finally got to him, he had no escape after all. Regulus let his head fall back, breathing once again the dense air of the clouds. 

“Are you coming down with me?” 

Down. 

“To the netherworld? Do I have any other option, fiend?” 

“I’m not a fiend, Reggie. But you do have way more options than you think.” 

“Then who are you?” Reggies asked, feeling drunk.

“I’m just James.”

“James’ a nice boy.” Regulus giggled, trying to come back and focus on the shape barely a few centimetres in front of him.

“I’ve been called worse.” He mused. “Is it true Reg?" He asked after a bit of tense silence. "What Barty was bellowing? This whole time? You actually…” 

“Is it true that I fancy you? That I've gone completely mad for you? I’ve been accused of worse.” Regulus pleaded, biting his lip.

He heard the heavy breathing coming from the cloud pounding in his ears, growing rugged as two hands started pulling his broom. He finally came face to face with not an angel, not a fiend, but the sun himself. 

“Reg…” James begged, cupping his face with one hand. Regulus leaned into the warm of it, cause how could he not when the sun was so generous to him. 

“Please, James.” He begged back. He was begging James not to hurt him, to be gentle, to not drop him, to not let him shatter, to give him just a bit more of his  warmth. 

James gave in and the clouds seemed to dissipated around them as he leaned for his mouth, a tentative press of warm lips that quickly turned into a burning fire. James chased him and licked into his mouth as if he was determined to burn him alive. Grabbing his face and his back with such hunger that Regulus' hips kept being lifted from his broom. 

“Wait a minute.” Regulus asked, trying and failing to get some oxygen in. “Nice boys don’t kiss like that.”

“Oh yes they fucking do.”