Hello! I'm back with a new story, yay!

Well not exactly a new story. This is a prequel to 'The one I need' (so obviously you don't have to read it to understand this one^^)

'The one I need' mostly focused on Sherlock and John, this one is focused on Mycroft and Gregory :D

I have kept certain plot lines from the books for this one, but you'll see ;) The story starts during Greg's second year (and don't forget that Mycroft is a year older)

Basically, John is in Gryffindor, Sherlock in Ravenclaw, Mycroft in Slytherin and Greg in Hufflepuff. I know that Greg, John and Sherlock could belong to different houses but I kind of like it this way ^^

And... I think that's all you need to know. Enjoy!

Disclaimer: I don't own anything. Harry Potter belongs to J.K. Rowling. Sherlock Holmes belongs to Sir Arthur Conan Doyle and this version of the characters belongs to the BBC, Steven Moffat and Mark Gatiss. I didn't make any money writing this.

A/N: A round of applause for my Beta, IBegToDreamAndDiffer :) She was a huge help, just go read her stuff it's amazing ;)

2nd year

Waving his parents goodbye, Gregory boarded the train and dragged his case along the corridor in search of an empty compartment. This was his second year at Hogwarts and the boy could honestly say that he was glad to be back. He loved his parents, obviously, but he had missed the magical world so much, he had missed his friends (rare as they were), he had missed the Quidditch games, the meals in the Great Hall. Hell, he had even missed his homework.

He enjoyed summer break as any kid would, but the muggle world didn't appeal to him anymore. To be honest, it'd never had. Non-magical folks were fine, he even had a few friends back home, but after having found Hogwarts, going back seemed almost impossible. He had found a place he never thought he would, somewhere he actually felt at home.

With a strong smile on his face, Gregory opened the door to the last compartment, excepting to find it empty. To his great surprise, there already were two boys sitting facing each other, and apparently in the middle of an argument.

"I told you not to bring your chemistry set this year! You almost got us expelled last year!"

"I still don't get it, I put the fire out fairly easily."

"You burned half of the bathroom down!"

"No one uses it anyway."

Gregory cleared his throat, getting the attention of the two kids. The taller one had a pale face, long dark and curly hair with piercing blue eyes. The other boy seemed much warmer (he actually smiled, which helped), he had short blond hair and a healthy tan. His eyes were a deep brownish color and looked more welcoming than any words ever could.

"Hi… er, sorry to interrupt. Do you mind if I sit with you? All the other compartments are full."

"I do, very much."

"Not at all, come in."

The two boys had answered simultaneously, startling Greg. The blond boy turned to glare at his friend who glared right back. But somehow, Greg felt that if the taller kid really was annoyed, the blonde's irritation was mixed up with a sort of… fondness. He shook the thought off and ran a hand through his hair, waiting for some kind of invitation to sit.

The blond kid turned to him. "Please, sit down. Sherlock is just a bit grumpy because his mother managed to take half of his stuff out of his suitcase without him noticing it." He chuckled a bit at the other's kid groan. "I'm John by the way, John Watson. And this is Sherlock Holmes."

Greg finally managed a smile and sat next to John, making a special effort to stay as far away from Sherlock as possible. He shook the blond boy's hand and tried to relax. "Gregory Lestrade. Nice to meet you both."

Sherlock grumbled something under his breath and John kicked him. "Don't mind him. So, are you a second year too?"

"Yeah, I'm in Hufflepuff." Greg let out a relieved sigh, feeling better with the knowledge that they were all in the same year.

"Oh. Well, I'm a Gryffindor, and Sherlock here is a Ravenclaw."

Sherlock puffed his chest a bit and Gregory grinned. He could almost read the 'genius' sign on the boy's forehead. John seemed to notice but fortunately for them both, Sherlock was oblivious. Clearing his throat, Gregory changed the subject.

"So, do you play Quidditch?"

"Oh for the love of God…" The Ravenclaw groaned, earning a chuckle from John.

"Sherlock hates it, but I play a bit at home. I really love it, I'd like to be on the Gryffindor's team but I don't think I'm good enough."

"Oh, we could practice together then!" Gregory nearly jumped out of his seat at the prospect. "My parents are both muggles, so I can't play during the summer, and of course, I couldn't try out for the team last year, but I'd love to play more!"

Gregory saw Sherlock roll his eyes and wondered if it was about the Quidditch or his muggle origins. Possibly both. But John seemed like a nice bloke, so Gregory let it slide. Sherlock seemed to complain a lot anyway, so it probably wasn't anything personal.

"Oh My God, that would be great! In this case, we both try out for our respective teams this year, and every year till we're in." John gave him a warm smile.

"Deal."

They both engaged in a long conversation about Quidditch then, their favorite teams, players, the broom of their dreams and so on. Gregory was so absorbed in their talk he nearly jumped up when he finally noticed the time.

"Oh shit. I better go and get dressed, we're nearly there."

John checked his own watch and cursed. "You're right. Well, it was nice to meet you, I'll get in touch when I can get the field to practice."

"Yeah. It was nice to meet you too. Both." He added, turning towards Sherlock. "Sorry I didn't leave you much time to talk to John."

He noticed the Ravenclaw's smirk and got out of the compartment. Sherlock shrugged off John's questioning look and decided that maybe Gregory Lestrade wasn't so bad. After all, he'd had the good sense to notice that John was his.

A few weeks after school had started; Gregory was coming back from his jogging around the lake, tired but feeling good about his physical form. He knew most kids would find it stupid of him to run around in circles to get in better shape, but Gregory liked it. He wasn't strong enough to be the Hufflepuff's goalkeeper yet, but he hoped, in time, he would be.

That was why he trained without John two days a week. John was already in better form than he was and Gregory had no doubt that the Gryffindor would make the team this year, but he didn't like his own chances so much. Letting out an exhausted sigh, he turned past the greenhouses and was quickly approaching the castle doors when he heard something that made him stop dead in his tracks.

It sounded like a fight, a few feet to his left. Actually, it sounded more like a beating than anything else. Gregory's stomach turned into knots and he swallowed hard, making his way towards where the noises came. He risked a glance and instantly froze at the sight.

Two kids (probably third years) were beating the crap out of a much younger kid. Or at least, he appeared to be much younger when Gregory saw how fragile he looked. The Slytherin boy (the youngest, he thought) simply stared at the other two as one of them punched him square in the jaw.

"Hey! Leave him alone!" The words were out of Greg's mouths before he even had time to consider them.

The two Gryffindor kids turned to look at him but the other boy stayed perfectly still, apparently uninterested in what was going on. Gregory swallowed hard, trying not to show his own fear and pulled out his wand, getting comfort from the simple gesture.

He raised an eyebrow in what he hoped to be a challenging look (it probably looked more funny than scary). However, the two boys apparently didn't want an audience; they turned to each other and shrugged.

"Almost done here." One of them sneered before kicking the Slytherin boy in the stomach. He fell over but never looked up, taking deep breaths.

The two idiots then turned their backs on Gregory and headed for the castle, chuckling. Gregory clenched his fist but decided it was wiser to let it go… for now. As soon as they were out of earshot, he ran to the other boy.

"Are you all right?" He put a hand on the boy's arm but the Slytherin jerked away, frowning at him.

"Don't touch me."

Gregory put his hands in the air, feeling like a criminal getting arrested and trying to prove he was unarmed. "All right, I won't touch you. But are you okay?"

"Fine." The kid's voice was so measured it was difficult to believe he'd just been given what must have been the beating of his life.

He got up to his feet, his legs shaking a little but with quite an impressive air of authority for a kid in his state. Gregory's hand immediately snapped up, trying to keep him still but he stopped in mid-motion, remembering the kid's reluctance to being touched.

"Are you sure? Do you want me to get you to the Infirmary?"

The Slytherin frowned at him as if the idea seemed completely ridiculous to him. "Of course not, why would I need to go to the Infirmary?"

Gregory's jaw dropped. He wasn't sure if this boy was just proud or plain stupid, but he wasn't about to let him walk away so easily.

"Can I try something? I promise it won't hurt." Gregory gave him his softest smile and waited for what felt like forever under the other cold gaze.

"All right." He finally answered.

Gregory poked him in the stomach and the kid visibly winced. "Ouch. You said it wouldn't hurt!"

"Yeah, I lied. See? That is exactly why you need to go to the Infirmary."

The Slytherin boy glared and Gregory grinned in response.

"Come on, I won't let you go back to your common room in this state. You might have a broken rib."

The kid sighed. "It does seem to be the most logical course of action."

At that remark, Greg's eyes nearly popped out of his head. The most… what was the kid on about? He'd just been beaten up… incredible. Maybe he really was an idiot, although, something in his eyes told Gregory this was impossible. Somehow, they reminded him of someone but he simply couldn't remember who. He shrugged it off and moved to take the other's arm in his but once again, the kid jerked away, frowning at him.

Gregory sighed. "Look, I won't hurt you. I really promise this time." He smiled despite himself. "But unless you want a broken ankle to go with your ribs, I suggest you lean on me until we get you to the Hospital Wing. All right?"

The kid stared at him for the longest time, his face completely unreadable, and for the first time, Gregory felt that maybe the boy wasn't as young as he'd thought. There was something very grown up about the way he stood, and his eyes spoke of past experiences, not all pleasant ones.

After what felt like an hour, he finally let out a sigh and straightened his clothes, at least tried to, and put his hand on Greg's shoulder. Greg circled his arm around the Slytherin's waist and supported most of his weight as they limped back towards the castle. They walked in silence for at least five minutes, until Gregory couldn't take it anymore. There was one question he'd been dying to ask.

"Why didn't you fight back?"

The kid turned to him with a look of surprise on his face. He shook his head and started walking again, staring ahead. "I couldn't beat them, there was no point."

"That's bullshit." Gregory frowned and missed the utter shock displayed on the other's face. "Even if you can't win, defending yourself is a human reflex; you can't just lie back and take it without a reason."

The other kid kept silent and walked on until they were at the Infirmary's doors. "You can let me go now, I'll be fine."

Gregory actually chuckled at that. "Don't be stupid, it's only a few feet away. I don't care if you're embarrassed; I'm not letting you go."

He practically had to drag the Slytherin boy to a bed, but he made it. When the kid was finally lying down, he called for Poppy and the woman barged in the room, making a fuss.

"For the love of Merlin, what happened now? Did someone hit him?" She turned towards Greg, knowing the other kid wouldn't be honest with her.

Gregory opened his mouth to tell the truth but then noticed something in the kid's eyes. A flash of hurt, and somewhere deeper, shame. The Hufflepuff cleared his throat and focused on the nurse once again.

"Er… no. Actually, we were on the Quidditch pitch, he was helping me practice and I shot a Bludger at him. It was an accident, I swear! So we stopped and I brought him here."

Gregory could tell Mrs. Pomfrey wasn't buying any of it, but he was entirely focused on the Slytherin boy now. He was looking at him with the most unguarded expression he had ever seen the other kid wear, and this time Gregory could read him perfectly: he was grateful. Greg smiled despite himself and heard Poppy groaning in the background. She set off to get what she needed and Gregory saw the boy's mask fall down for a moment.

"It's because of my brother." He whispered, looking away. "He fights… all the time. I don't want him to think it's okay."

Even if he wasn't sure he understood, Gregory nodded. After all, it wasn't any of his business. He saw Poppy come back and grinned at the Slytherin boy.

"I'm Gregory, Gregory Lestrade. Nice to meet you."

"Nice to meet you, Gregory."

The Hufflepuff barely had time to smile before Mrs Pomfrey was shooing him out of the Hospital Wing. Gregory went back to his own common room, noticing with a slight frown that the other kid hadn't told him his name.

There, that's all for now. I have finished this story (all 12 chapters, yay!) and will probably upload one new chapter each day :)

If you could take the time to leave a review, I'd really appreciate it :)

And... see you tomorrow I guess :D