30 YEARS AGO…

Sirius wasn't even sure how it happened. It certainly wasn't the first time he had ended up in detention with Severus Snape, but it was the first time a teacher decided to give them detention for a solid five months and merlin damn it, the whole thing wasn't even his fault!

Because they were in close quarters, the teenagers agreed to a truce—No point in getting further detention—And over the tiring nights, something changed.

It started off with little things. Severus slipping while cleaning and Sirius catching him before he struck his head against the desk. Severus humming muggle music, only for Sirus to be surprised to find they liked the same bands. Realising they liked the same muggle author's and both hated vegetables. Three weeks in and Sirius learned Severus was abused by his father. It cut so close to his own backstory, that he started to see the Slytherin completely differently and by the time their detention was over, they were friends.

For fear the rest of the Marauders would freak, Sirius kept quiet and since he was in no mood to listen to the Slytherins bitching, Severus said nothing either. They found ways to meet in secret. Passed notes to each other and eventually gave into a desire that caught both of them by surprise.

It had felt so right. Merlin damn it! It was like coming home. Sirius had never desired anyone the way he had Severus in that moment. Every kiss, every touch, it was nothing short of masterful.

So naturally…the fates had to destroy it.

It had been a week after that night. Caught up by schoolwork, Sirius thought little of it, beyond the fact that they were both busy, until an owl found him in the library, and he had felt a thrill of excitement. Severus had reached out! Eyes flitting over the parchment, he felt giddy. He wanted to meet! The astronomy tower at ten!

This was it. They'd make it official, and his friends would just have to deal with it, because there was just something about Severus that Sirius wanted to get to know, to keep, to have forever.

"What's gotten into you?" James asked when Sirius bounced into the Gryffindor common room an hour before he was due to meet his snarky Slytherin, hazel gaze looking up from his transfiguration homework. "You've been down in the dumps all week, now you're acting like you just ate an entire box of sugar quills."

"Nope Jamie! The last time I did that, I was spectacularly ill…" Sirius reminded him cheerfully. "We promised we'd never repeat that faithful day. Remus swore he'd skin me alive, didn't you Remy?"

Startled from his potion's book, Remus frowned at his friend. "You, mate, are wired…too much pepper up potion?"

"That was one time!"

"Twice, actually," Peter corrected from where he lay sprawled on the floor, trying to get his own homework done. "Remember last Christmas?"

"What happens in the shack, stays in the shack!" Sirius warned, horrified, making his three best friends laughed.

Setting his work aside, James stretched, eyes locked on the dog shifter. "Seriously, Pads…what's going on?"

Squirming under his friend's scrutiny, Sirius wanted to tell him, tell all of them…just not yet. Not until there was something to tell. "Something great…hopefully…you'll know soon, Jamie, I promise."

James watched him a moment. He itched to know what was going on, but he trusted his friend and he respected his privacy. "Alright Pads, we're holding you to that."

With a nod, an excited squirm, Sirius darted upstairs to the sixth-year dorms and hurriedly got ready. Some rooting and he grinned in delight when he found what he was looking for. The Black ring on a pretty silver chain. He was no doubt jumping several damn steps, but Merlin, he didn't care…He never expected Severus Snape of all people to be his perfect other half and yet, here they were. Pocketing the trinket, he took one last look at himself in the mirror and rushed out, hollering a quick goodbye to his mates.

The castle was pretty quiet. At this hour only sixth and seventh years were permitted to be outside of their Common rooms, as were the teachers and with the Winter well under way, it was already dark. By the light of the sconces, flames flickering, Sirius made his way up the stairs of the astronomy tower and found it secluded.

He expected as such, he was early, so it didn't worry him.

The night was stunning. The sky clear, stars shimmering, and a brilliant moon lit up the top of the tower. There was just something perfectly romantic about it.

"You're here."

Heart stuttering, Sirius turned and grinned at the sight of Severus leaning against the archway. Still in his uniform, the teenager looked bored. Warning bells went off in his head, but the dog shifter shook it off. "I wanted to see you, little snake…" Sauntering toward him, he grasped Severus' sleeve and tugged him forward, intent on a proper greeting, only to be shoved…hard!

"Don't call me that!" Severus snarled, watching the startled Gryffindor stumble. "You think I wanted any of this?!"

Pain twisted Sirius' insides. No. That couldn't be right. The Black ring suddenly weighed a tonne in his pocket, and he was positive his heart had shattered. Still, he tried. "V-Very funny, little snake…You have a twisted sense of humour…I always said that. Are we going to have a real conversation now?"

Severus snorted. "What conversation? About my mistake, or the fact I wasted my time on a sorry excuse for a pureblood. Since you're hard of hearing, Black…Let me spell this out for you…it will never happen again!"

No, no! Why was Severus being like this? After everything! "If you don't want to pursue a…a relationship, fine…but nothing stops us being friends." Merlin, he sounded like a begging mutt, how pathetic was that? "Don't do this…please, Sev…please!"

"Typical dog," Severus sneered. "Gets kicked but keeps coming back. Not this time, mongrel. Don't dare approach me. Don't contact me, as of this moment, you are to stay away from me…am I clear?"

Numbly, Sirius nodded. He barely noticed when Severus had left…or when he had sunk to the floor. When the tears came, he just let them fall.

PRESENT DAY….

Severus paced in shock. Sirius sat, hands shaking after hashing out what had always been a shite memory for him and in all honesty, the stunt he'd pulled with Remus suddenly made a lot of sense. Merlin knows, he'd have been just as vicious had someone hurt him in the same manner…but it wasn't him!

Spinning to face him, hair mussed from the hand dragging through it, Severus cursed colourfully, before trying to defend himself. "Sweet Merlin's balls and Morgana's tits! It wasn't me! A snarky bastard I may be and was even then, but I wasn't the cruel type unless others were cruel to me first and…that had changed between us! We were friends!"

"I know!" Sirius exploded, bursting up, stalking up and down like a trapped Lion. "But I didn't imagine it, Snape! You were there! Shouting things only you knew!"

"You think things aren't found out?" Severus demanded incredulously. "Hogwarts is like a small village. Everyone knows everything!"

"It was you! It—" Struck by something, Sirius' complexion ran grey and with a curse he dropped down onto the couch.

"What?" Severus demanded.

"… 'Typical dog' …You…he…Merlin only fucking knows…. said to me typical dog…as well as called me a 'mongrel' …" Sirus dropped his head back pinching the bridge of his nose. "I was so fucked up I never noticed…but you hadn't known I'm a dog Animagus. Not at that time…Not until last year…in fact, only three knew I was…Remus, James, and that rat bastard Pettigrew."

Severus sucked in a breath when an old memory hit him with a smack. "A week before the…the whomping willow debacle…I could have sworn I saw Pettigrew messing around Slughorn's stores…I wasn't sure and since I was still holding out hope for…us…I stayed quiet. Rumour was some of his premade Polyjuice had gone missing."

"Pettigrew the complete moron was so twisted up about loyalty. At that time, he'd have seen you as a threat and would have thought he was protecting me…" Sirius snarled. "Wouldn't be the first time he followed us when we were doing our own thing and did something stupid. I can't count how many times Jamie started shite with you because Pettigrew fed him some false bullshit that he knew would hack him off. 'Course it wasn't till seventh year we figured that out. Led to a huge blowout."

Severus blinked in surprise. "Really?"

"Oh yeah…Pettigrew apologised eventually, and we mended fences…or so we thought…Hindsight is a great thing." Sirius scoffed. "He managed to trash our lives back a lot further than any of us knew…Fuck! I am so sorry! If I had just talked to you that night…Instead I let my rage get the better of me! We could have raised our kid…. been together…"

Severus was astounded. Sirius Black was actually apologising. Miracles never ceased. Wincing at his own snarkiness, reminding himself they had been victims of someone else's interference, Severus moved to sit next to him. He'd never noticed before, but unlike when they were teenagers, he was now a full head or so taller than Sirius, but the man was still blockier.

"I suppose…" Severus started, not sure where to begin, but to hell with it, he took the plunge. "We draw a line and start fresh."

Head snapping up, Sirius positively gawped. Was Severus really offering him something so sacred? Common sense would've meant starting from step one, but Sirius logic had that flying right out the window and yanking the man toward him to crash their lips together in a fiery kiss.

He expected his balls to be hexed off, but warmth immediately flooded him when Severus kissed back. The taller Wizard sliding into his lap such a familiar sensation that Siris groaned with hunger. His hands fisted in long dark hair, lips taking feverishly, until—

"GET A ROOM!"

Springing apart, tussled, and breathing heavily, Severus and Sirius set their gazes on the one who shouted. Katsuki stood, Eri's little face pressed protectively into his shoulder glaring at them both, while Hitoshi along with Hizashi absolutely howled with laughter. Next to his brood, Aizawa raised a brow and said dryly. "Use a condom…I'm too old for a baby brother or sister."

"Don't encourage them!" Katsuki spluttered.

"Aww, don't worry, kiddo," Sirius grinned, tossing an arm about Severus' slim waist and loving his crimson cheeks. "Silencing charms are a thing."

"Daddy?"

"Yeah, Eri?"

"…. What's a condom?"

-SING-ME-HOME-

The next day, shoulder still a tad achy, Izuku rushed through the halls of Hogwarts and made it to Transfiguration just before the last student stepped inside. He had missed most of his morning classes due to Madam Pomphrey fussing, as well as Hizashi insisting he stay put, but thanks to Aizawa and Severus he eventually made his escape. He had never been one to sit idle, not even for a severe injury and honestly, he had been up and about after much worse during the Sport's festival and after the Camp incident. The Chimera bite was nothing.

"Oh! Izuku! Over here!"

Catching sight of Hermione, Izuku smiled. She had saved him a seat by the looks of it. Dropping down next to her, he noted the small group either side of the classroom. Some in military style and others in powdered blue…this must be the two other schools. Whereas the girls in the blue paid him no mind, he couldn't help but notice the others were staring.

"Hey mate!" Ron greeted from behind him. "How's the shoulder?"

Shaking off the foreboding feeling, Izuku grinned back at him. "Not too bad today. Honestly, I've had worse in Hero training."

"I bet," Harry snorted. "Your brother let some slip…two shattered arms?"

Cheek's pinking, Izuku hurriedly pulled out his books, ignoring Harry's warm laughter and the nice little flutter it sent through him. As well as his books, he pulled out a thick notebook already colour coded, named and half full. Hermione beamed when she saw the English scrawl underneath the Japanese… 'Hermione's notes.

"You've been busy I see."

Izuku chuckled. "Yeah…I had a lot of time between yesterday and this morning. I've gotten down the first two years so far..."

Jaw dropping, Hermione squawked a noise. Ron and Harry were equally stunned. "Two years…and…and you understood it? Every subject?"

Izuku nodded absently. "I want to give everything another read through before I try any of the spells of course and I need to borrow some books for some deeper…why are you all looking me like that?"

Hermione, Ron, and Harry stared at him with awe. Ron was the first to break the moment with a snort. "Well, it seems there's someone who likes to study more than you, Hermione."

Both Izuka and Hermione flushed darkly. Mouth opened to protest; Hermione quickly closed it when Professor McGonagall breezed in. "Books opened to page eighty-three, and students of Beauxbatons and Durmstrang, look it with a Hogwarts student. Welcome Mr Aizawa, you're looking better."

Flushing under the sudden scrutiny of the other students, Izuku shifted in his seat. "Uh, yeah…thank you…uh…Professor."

With a curt nod toward her newest Lion, McGonagall flicked her wand toward the board, the chalk springing to life to scrawl instructions. Izuku opened up his thick notebook to the section he'd already begun for forth year and started scribbling away.

The Switching Spell…The incantation in Latin was Unus pro alio, which translated to 'one for another.' A transfiguration spell used to switch the positions of two objects. The concept was simple enough to understand and Izuku was already visualising the multiple benefits of such a spell, pen scratching over paper as he worked. It was all so fascinating to him. Magic could achieve a lot in abundance for one person, that many people could with individual Quirks. He couldn't wait to see how he could apply it to his Hero training.

"So!" McGonagall began once the chalk had finished its job. "Reading what is on the board…can anyone tell me a benefit to such a spell?" When Izuku's hand was one of the first to rise, she blinked in shock. For someone only dipping his toes in so far, she figured he'd be quiet for a while, yet here he was, diving right in. "Eh…yes, Mr Aizawa?"

"Protection!" Izuku bubbled cheerfully. "If someone had a weapon or…or their Wand…you could switch it for something else like a…a feather duster, to protect yourself. Of course, the Wand would be trickier being a magical object…Then there's the lethal applications in the wrong hands where…well…someone could switch out your heart for a tennis ball and kill you instantly."

"A fact they don't mention in your books," a Durmstrang student commented idly, grinning over at Izuku. "You've a dark mind."

Izuku frowned. Everyone bar the Durmstrang students were looking at him strangely. What was wrong with what he said? "Not dark…" He corrected the other boy. "Just understanding the spell from every angle. Aren't we supposed to?"

"One would think."

"That's enough," McGonagall snapped. "Thank you, Mr Aizawa, for that…description…Now, the wand movements required…"

Izuku listened, albeit reluctantly to the rest of the lecture. What had he said that was wrong? The rest of the Gryffindors, apart from Hermione, Ron and Harry were looking at him strangely. Whereas the Slytherins had curious expressions. Feeling a nudge, he glanced down. Harry had slipped him a scrap of paper and mindful of watching eyes, Izuku unfurled it gaze darting over the messy scrawl.

Don't take it personally. McGonagall can be harsh.

That was putting it mildly. Very aware he had committed some sort of slight, Izuku kept his head down. When the bell signalled, he was the first out.

"Izuku! Wait up!"

Stopping, Izuku watched Harry rush to catch up with him, alongside Hermione and Ron. "Look," he immediately defended. "I don't know what the big deal is. I pointed out the negative of the spell…so what?"

"It's because the switching spell is a light spell," Hermione explained. "Witches and Wizards don't like hearing a light spell can have…darker usages."

Izuku blinked. That was their hang up? That was stupid! "That's ridiculous. Magic…like a Quirk…can be used either way…it all depends on the user. It's stupid to categorise them as one or the other. I read through the standard book of spells from first year and a lot of them could be used for both."

"That's what I said!" Harry exclaimed, remembering a conversation he had in first year when he made the mistake of saying the exact same thing. "But nooooo, you're not supposed to say that. Thank you!"

Izuku laughed, glad one of them got it. "Yes! Exactly!"

Hermione and Ron fell into step behind the boys and watched in amusement as Harry lit up in a way he hadn't before, delving into a topic on light VS dark definitions in regard to spell work, they chatted animatedly the whole way to Charms. It was honestly adorable.

"Books out! Wands at the ready!" Professor Flitwick called out, perched on his usual stack of books. "Today we will be touching up on our summoning charm. Oh! Welcome, you must be Izuku Aizawa…?"

Shaking himself out of a stupor after he had momentarily gawked at the tiny Wizard, Izuku gave a hasty bow, before taking a seat next to Harry. "Hai…I mean, yes…yes, I'm Izuku Aizawa."

"A pleasure! Now, just to catch up Mr Aizawa…we are practicing the summoning charm today. Accio." Flitwick smiled. "Would you like to give it a try?"

Blinking in surprise, Izuku shifted nervously. He had yet to attempt any magic and had already been warned that there was a potential for overpowering his spells by accident, but hey, it wasn't like he hadn't dealt with worse backlash. At least any damage would be outward rather than inward. No broken bones to worry about.

With a nod, Izuku rooted out his wand and waited for Flitwick to explain the basics of the spell. His brain logged away everything, running through all components and focusing on a cup upon the Professor's desk, he raised his wand, and confidently cast the summoning spell.

"Accio cup!"

Months of honed instincts was the only thing that stopped the porcelain smacking him right in the face. With a gasp, Izuku snatched it out of the air and grinned in delight. He had done magic!

"Oh! Well, done, Mr Aizawa!" Flitwick praised. "On your first try! Alright! Everyone, each pick out a small object and the person beside you should each try to summon it."

It was chaos and the most fun Izuku had in a long time. For some the spell didn't come easy and to others, like Izuku it came too easy, which led to quills, trinkets, all sorts of items whizzing all over the room. More than once, poor Professor Flitwick ended up diving for cover. By the time the bell went, the green haired teen had forgotten the weird behaviour in Transfiguration.

-SING-ME-HOME-

Stomping through the halls, kitted out in his Hero gear and fully aware he was drawing looks, Katsuki searched each face for his brother. He knew the last class had just ended and he was itching to train. Hitoshi could be a good spar, but to give his Quirk a full workout, he needed Izuku.

Catching sight of a familiar head of hair, the ash blonde grinned and without a care, hollered loudly. "HEY CURLS!"

Jumping, Hermione spun around, eyes wide and jaw dropping at the sight sauntering toward her. The girls around her swooned because if Katsuki was a stunning specimen in just ordinary clothes, which was nothing compared to his appearance in Hero gear fitted tight to steal like muscles.

"K-Katsuki!" Hermione stammered, red staining her cheeks. "Um, did you need something?" Merlin, she could all but feel the blazing heat off of the other girls.

Katsuki grinned roguishly. "Have you seen my little brother? Know your classes are over and he owes me some training. Your Headmaster gave us permission to use the grounds."

Fascinated, Hermione positively wiggled. "Wait! Training, can I watch? I'd love to see how your Quirks work!"

"Sure, Curls…Just keep back. Dumbledore is setting up a safety barrier, don't go past it."

"Brilliant!" Hermione beamed, grabbing his gloved hand, and pulling him through the gawping crowd. "He's in Gryffindor tower with Harry."