The Patronus is an ancient and mysterious charm of protection that shrouds the caster in a light composed of all the happiest memories of their life. Harnessing the power of the good may be the most difficult skill to master when learning this advanced magic, especially when faced with a foe that feeds on it, like a Dementor. No one knew when or where they would have to have a stand-off with one, but they had to be prepared for everything.

There was going to be a war, after all.

It had been raging for years. In the shadows, in the sky. Innocent Muggle families murdered, the dark mark proudly displayed over the scene of the crime. He Who Must Not Be Named recruiting everyone from Ministry officials to Hogwarts students. Even creatures – not just the guards of Azkaban, but Giants, Acromantula, Inferi. Werewolves, too.

Remus would never be one of them, which was why in between classes, studying for his O.W.L exams and his moonlight transformations, he was part of a group which met every weekend to practice the kind of magic they would need on the front lines of battle. Being fifteen, sixteen, seventeen years old; it didn't matter anymore. They could ignore the warning signs all they wanted, but it wouldn't do them any good when push came to shove.

His classmates conjured non-corporeal Patronuses all around him, and while they didn't provide the maximum level of protection, they had to remember that a lot of wizards and witches were never able to produce more than the wisp of light, akin to a translucent, white smoke. It was better than nothing, but Remus wasn't satisfied himself – how could he be, knowing the power of truly dark magic?

The wolf stirred in him, but it only wanted to wreck havoc on Remus' body, not the Muggle born population of England, so he suppressed it. The full moon was approaching, and he shouldn't be expending all his energy working on charms as difficult as the Patronus, but picturing the most recent gruesome attack that had been reported in the Daily Prophet, involving three rogue Dementors and a family living in Sussex, motivated him to push through the tiredness. No one should have to face that fate. Death was cruel, but the Dementor's Kiss made it look like mercy.

The problem was that the wolf didn't inspire happiness in Remus. Remus was actively miserable, and he couldn't ignore the cause of it, not while it taunted him from the inside out. First your mind, then your body, completely unrecognisable. Another night in the shrieking shack, tearing off his own skin.

His friends had learned to become Animagi. It was unfathomable, both illegal and impossible, that three fifth year students could master such Transfiguration. A stag, big, bold and proud like James. A rat, quick witted and devious like Peter. The dog, loyal, excitable, fierce. Just like Sirius.

His wand tingled in his hand, and he waved it in a circular motion. Expecto Patronum. Just a wisp, as bright as it was, it still took no form. Remus gripped it tighter.

The only problem with the fact that his very best friends could now become Animagi to accompany him on his worst nights was that he hadn't allowed them to in months. They had mastered the art at the start of the school year, and Remus had been so excited, he could feel it in his chest; heart beating a million miles an hour. His friends, his pack. Freedom. The wolf wanted to run wild, wrestle with the stag and nip at the dog's heels as they covered acres and acres of the Forbidden Forest. The wolf needed a distraction from attacking itself.

But things weren't the same since what happened with Severus Snape. The trust, it dissipated. Sirius wasn't a stupid person, but he made stupid mistakes, and Remus couldn't hold that against him – he was a teenager, angry and confused and provoked and miserable, with a hundred other things going on in his life, and he just snapped. He didn't even know what it was that he had done until he returned to Gryffindor Tower, whistling, a huge grin on his face, ready to brag about his latest act of mischief. "The nosy git is gonna pay for being such a bloody nuisance, just you wait," he had said.

"What did you do?" James didn't know the severity, so he took on the same beaming smile, bright eyes. He loved nothing more than making Severus pay for being, well, Severus, but even this was too much for him to agree to.

"He knows just where to go if he wants to confirm his brilliant theory. He'll never mess with us again."

Peter's normally pale face went very grey. "Sirius. What did you do?"

They were able to intervene before anything bad happened – well, it was all relative, Remus supposed. In the end, all it served to do was confirm Severus' suspicions that he had held for years, at least since their third year, maybe earlier – he was even sworn to secrecy by the Headmaster when he got wind of the 'prank'.

Sirius had effectively outed his condition to a person who was obsessed with exposing him for the beast that he was, and Remus didn't know how to forgive him. Not when Sirius had been the first person he trusted with his secret. The Astronomy Tower, New Years Day 1972. They were first years. They were scared. Sirius was worried – noticed the scars, caught Remus out in a lie. Brought him somewhere safe, late at night, to show him that if he felt comfortable sharing whatever was on his mind, it would never leave that room.

So Remus came clean, and told him. The scars on his face, the ones he returned from winter break with that Madam Pomfrey couldn't heal, they were werewolf marks. Self inflicted. They had only known each other a few months, not long enough for Sirius to notice a pattern where the dates of his various ailments lined up. A gastrointestinal problem here, an unwell parent there. White lies. Leading up to a transformation, everything hurt – his stomach, his head, his muscles. And his mother was unwell, a wicked illness that he could barely stand to watch her slowly succumb to.

The thing about friendship was that Remus didn't know what it was all about until that night. After he was bitten as a child, his parents had moved him around, village to village and county to county, avoiding suspicion and shame. He wasn't allowed to befriend the local children, even if he had been, he wouldn't have wanted to knowing he'd be relocating within months. The only shred of normality was offered to him in the form of his Hogwarts acceptance letter; something that was surely a mistake, because how could they admit a monster to a boarding school? Remus' dad had been resigned to providing him with a basic magical education at home, that was the plan – until Albus Dumbledore, the headmaster with a long beard and twinkle in his eyes, showed up at their doorstep.

Remus had played Gobstones with him that day, not taking any notice of the serious conversation taking place between the three adults in the room. There had been special arrangements made for him. He had somewhere safe to undergo transformations. No more basement.

No more basement.

Making friends at Hogwarts seemed pointless, though, and Remus wouldn't have dreamt of it were it not for Sirius. Sirius was always a boy who sparkled, who made you feel better just by entering a room – let alone by looking at you. Speaking to you. Quick, intelligent, full of questions and opinions and so much trouble, so much attitude. Remus had shared the train ride on September 1st with just Peter, but from the time of the feast, he found himself in a real group. Four boys who slot together like pieces of an odd jigsaw puzzle. He didn't expect himself to spill his guts to one of them within months, and the others within a year.

That was the thing. Sirius had respected him. Not just by not recoiling in horror at the idea of what he was once a month – even though anyone in his position had the right to do so – but by understanding Remus not wanting to tell the others yet. There wasn't even a question, he hadn't pushed him, which was so unlike Sirius, because if he thought something was the right thing to do, he never made a secret of it, but he had taken a rare, gentle approach that night.

They had been more than just friends since then, not best friends though. Sirius had James. James was his best friend, everyone knew that. Remus could never put a word on the bond he felt with Sirius, just that something had stirred within him when they lay on the floor of the Astronomy Tower, Sirius pointing at the moon, a Waning Gibbous, telling him how the thing he feared was about to grow smaller and smaller – and had to grow to full size all over again before he had to worry and face it. Sirius then pointing at the brightest star in the sky, to the left of their view.

"You see that star? The bottom left, the brightest one in the sky?"

"It's Sirius."

"It's Sirius," he affirmed. "Of course, my parents named me after the brightest star before they realised what a colossal shit stain I'd be to the Black family."

"Don't say that-,"

"It's okay! It's true. I don't care. Anyway, my point is, no matter what phase your moon is at, that moon that controls you more than you wish it did – I'll be right there."

"Canis Major."

"Huh?"

"Sirius; it's in Canis Major. It means big dog."

Sirius burst out laughing. "Maybe we were meant to be friends all along, hey?"

They were looking at each other now. "Well, you shouldn't ignore what is written in the stars."

Sirius already had his best friend, so Remus could never fill that role. James was that person from day one, from when they met on the train, they told that story all the time. Where did he fit in Sirius' life? Why did he feel so much closer to him than anyone else he knew?

The wand in his hand felt hot again, the warmth spreading up his arm. The Astronomy Tower. Was that a happy memory? Remus supposed it was. The happiest, in fact. The most free he had ever felt in his life, bar that first time they had ventured into the Forbidden Forest, all in their animal forms. He had gotten something off his chest, something that was killing him, and Sirius had accepted him, had promised to keep him safe, shown him the moon…

Sirius.

"Expecto Patronum," the incantation was barely a whisper when it passed Remus' lips, but it was enough. A mere wisp of light no more, a stream of bright white burst out of the tip like a crashing wave, and from it, a four legged creature emerged.

What was it? A wolf? How could it be a wolf? The Patronus was meant to be a protector, and the wolf was the part of himself that he hated, the part he feared so. Four legs, a tail, pointed ears.

Oohs and Ahhs echoed around the room as the students stared at the Patronus, running laps around desks and cauldrons before returning to stand protectively in front of Remus. It wasn't until it looked back at him, head cocked and eyes mystical, there and not there at the same time, that he realised what it was.

"Nice dog!" Sakura Matsuyama called from the other side of the classroom, clapping with enthusiasm. "Wait 'til I tell Regulus you were the first of us to do it! He said if it wasn't him, it'd be you...,"

It wasn't the wolf. His features were too friendly, too familiar, too playful. It was uncanny – "Padfoot," he whispered, before it disappeared in time with the focus Remus was losing to sustain the spell.

Sirius had broken his trust all those months ago, but just because Remus' stubborn head refused to forgive him for using his affliction to gain revenge on a slightly annoying Slytherin boy that James loved to torment, didn't mean his heart had forgotten everything he had done for him. Just the vision of that ghost-like dog, taking its proud place in front of Remus as his protector, was enough to remind him of all the things Sirius had done for him. Everything he felt for him.

Sirius had acted in the heat of the moment, and it hadn't occurred to him that he would be hurting Remus in the process. Over and over again, he'd tried to tell Remus that – and he couldn't hear it. Not until he realised it for himself.

"Are you okay, Remus?" Sakura approached him. "You're shaking. It's pretty cold in here, right?" She threw him her Slytherin house scarf to wrap around his neck. The dungeon classrooms did remain freezing, even though spring was well underway, but he doubted cold was the reason for his tremors. Still, he gratefully clung to the material.

"That was difficult," he managed to muster up a reply. "Takes a lot out of you, 'tis all."

"What's the secret? If anything, at this point I just want to know what my Patronus is. For a second, I thought yours was… the wolf," she dropped her voice. "But I knew that wouldn't make sense."

"Me too. Uhm, the secret…," Remus scratched his head. "Do you have a memory in mind?"

"Well… it's not been a great year, has it?" Sakura was smiling, sadly. "I was trying to remember when things were carefree."

"Come on, Kura. Things around here have never been carefree. You need something solid – nothing shrouded in doubt or darkness or uncertainty."

"There's a few things… I suppose when I found my brother again, though that was just confusing for a long time. Or when I met you guys, but again, I was just a bitter little eleven year old who thought you all hated me for a good while, so…,"

Remus laughed. "It's hard, right?"

"Maybe Reg…," Sakura mumbled.

"Hm?"

"When Reg told me he loved me. It wasn't long ago, but it's the only thing that's happened this year that knocked me for six in a good way. I could barely think of what we were going through, whatever it was that lead to him confessing that… could it be that?"

Love. He studied Sakura's face, her pink hair now matching the bright shade on her cheeks, her relaxed shoulders, her unintentional smile as she thought of Regulus. He imagined her heart working overtime in her chest, the same way his did when he thought about Sirius…

Wait. The same way?

"You guys love each other," Remus said, slowly. "It's pretty obvious, you know, when we all see you together… we all knew you were a couple since last year and all."

"Good. We weren't trying to hide it," she grinned. "What is it with us two and the Black brothers, hey?"

"What do you mean?" Remus' voice was defensive, and stuck in his throat, but it just made Sakura laugh.

"I'm not stupid, Rem. I see it. The way you freeze when he's around, the way you look at him. Reg hears how Sirius talks about you. We have a bet on, and if you two could get together by the end of this year, he'll owe me 10 Galleons – he figures Sirius is far too stubborn to admit to his feelings before we graduate, but I told him there's no way you two will last that long. Just think about it. Sirius loves proving Regulus wrong, too, they're siblings after all, so it's a win-win… plus, I don't have 10 Galleons. I don't exactly have access to the Black family fortune."

"Sakura," he breathed. "Does everyone know? That I'm…?"

"No," she waved, easy going. "Reg just reads between the lines of everything Sirius says, and I'm observant. We connected the dots that you two are clearly obsessed with each other. Seeing the dog as your Patronus… it just all makes sense."

"Sirius thinks I hate him, though."

"He hates himself for what he did to you. He doesn't expect forgiveness, he just craves it. He wants to make it up to you, but only if you'll let him," Sakura sighed. "Only you can know if you're capable of that, though, Remus."

He paused. Maybe, it was time. "Where is he now?"

"He's in the library, he and Regulus are studying that book about- oh, you're welcome!"

Remus turned on his heel and sprinted out of the classroom, almost sending his wand flying out of his sleeve in the process, not letting Sakura finish her sentence but shouting a rough "Thank you!" before flying out the door. The library, the library. He didn't care that he was interrupting their research, even though it was surely important, he felt a new energy bloom, and it was clouding his judgement and all sense that he thought he possessed in abundance. He was muttering to himself as he climbed the marble staircase.

"My Patronus is a bloody dog."