Chapter 1: Hogwarts

Castor Black sat at the table in his kitchen, piles of books surrounding him and obscuring him from the sight of anyone who might wander in. His finger was on the page of an open book, following along as his lips soundlessly mouthed the words upon the page. After a moment he frowned before slamming it shut and tossing it onto the ever-growing pile beside him on the floor. He ran his hands over his face and through his jet-black hair, letting loose a low growl of frustration.

For almost a year now, Castor had been doing nothing but research on his nemesis, the man who called himself 'Lord Voldemort'. He was the Dark wizard who had murdered Castor's wife, his brother-in-law, sister-in-law, and tried to kill his son and nephew. Now, normally Castor wasn't one for revenge – nothing good ever came of it, after all. But, seeing as how the noseless bastard was trying to kill his sons – his biological one and his adopted ones – Castor had decided to put everything he had into bringing the man down.

To that end, he and his brothers – one by blood and the other by bond – had been working relentlessly to find the Horcruxes the git had created. He knew there were seven things old Moldy had put his soul into. Two had already been destroyed – both by his sons – two more resided in Castor's possession, locked up tight in his house, and another was housed in Castor's adopted son and nephew, Harry Potter. The last two, however, were a mystery to him.

The snake, the diary, the locket, and the ring. Cas recalled, wishing he had a cup of tea or something stronger right about now. They all have something in common. The snake, locket, and ring were all symbols of Slytherin – whether heirlooms or representations of the gift of Parseltongue his line has – and something Voldy would've coveted and held in high esteem. The diary was the tool he used to preserve a way to open the Chamber of Secrets, another link to Salazar Slytherin. Cas leaned back in his chair with a sigh, running his hand through his hair again.

"How's the research going?" a masculine voice asked.

Cas groaned in response as he heard the man sit down on the opposite side of the table. He could detect faint traces of sympathy dancing across the surface of the man's mind before they were swept away and locked away behind his Occlumency shields. Cas breathed a soft sigh of relief, once more finding himself glad that his brother had learned Occlumency many years ago. It was easier for him to focus when he didn't constantly have to barge in on the man's thoughts.

"Still nowhere," Castor finally replied. "We've traced his history. We know where he grew up, that he lived in an orphanage before he came to Hogwarts. We know about his family, we know why he put the locket in the cave, we know he worked at Borgin and Burkes -"

"I still wonder about that," spoke another man's voice, taking a seat in between Castor and his brother. "By all accounts, Tom Riddle was a brilliant man. He could've done anything with his life – why work at an out-of-the-way shop full of Dark objects?"

"Maybe he was looking for another object to put a Horcrux in?" the other man suggested.

"True, Padfoot," the second man conceded. "But that doesn't bring us any closer to finding out what that object is."

There was silence for a moment before the second man spoke again.

"I still think we should go to Dumbledore -"

"No, Remus," Castor cut him off sharply. "You know how I feel about him sticking his crooked nose in our business. We've found almost all the Horcruxes without him, we can find the last ones too."

"It was just a suggestion, Cas," Padfoot replied with an audible roll of his eyes. "No need to get your knickers in a twist." He was quiet for a moment. "How do you think the boys are doing?"

"Leo's probably failing his History of Magic exam," Remus said with a small chuckle. "I imagine Harry and Draco are trying not to fall asleep while they're doing their exams."

Castor gave a small smile as he listened to his brothers talk about his three boys, allowing the conversation to wash over him and soothe his weary mind. He closed his eyes, idly listening to the conversation as his thoughts went back to his History of Magic exam. I remember Rose had to rush me out as soon as it was done. All those thoughts – the anxiety and the worry – made me feel like my head was about to explode. We went to the seventh floor and found the Room of Requirement. There was loads in there – books, random objects, some accessories – it was the perfect place to hide from everyone...

Castor's brow creased as he frowned. There was a really ugly sort of tiara, I think. Rosie wanted to try it on but... just looking at it made me feel sick. I could've sworn I'd seen it somewhere before... and recently too... He wracked his brain, trying to remember. There was a book... a book about the Founders of Hogwarts... there were pictures of Slytherin's locket, Hufflepuff's Cup... and an ugly tiara – no. Not a tiara, a diadem. Ravenclaw's diadem. Wonder how it ended up back in the Room of Requirement...?

"Remus?" Castor said, cutting into his brothers' ongoing conversation. "Remind me again, where did Riddle go after Borgin and Burkes?"

"He applied for that Defense Against the Dark Arts position," Remus answered promptly, curiosity edging his voice.

"Why would he do that?" Padfoot questioned. "Dumbledore just became headmaster, he must've known there was no way he'd -" He cut off abruptly as a thought seemed to strike him. "Unless he wasn't actually there for the job. He was there for something else."

"Ravenclaw's diadem," Castor stated, feeling a mixture of giddy excitement and mild nervousness run through him. "He hid it in the Room of Requirement. I remember seeing it when I was with Rosie -"

"And what exactly were you doing with Rosie Evans all alone in the Room of Requirement?" Padfoot asked in a teasing sort of voice.

"What are we, five?" Castor rolled his eyes. "Grow up, Sirius. Anyway, we know what and where the Horcrux is. I say, we go up there and get it before some idiot stumbles across it and decides to put it on."

"We can't just waltz up to Hogwarts anymore, Cas," Remus reminded him with a small frown. "Dumbledore's not in charge – Umbridge is."

There was a very pregnant pause.

"... I'm still waiting on a reason as to why we can't go up there," Cas replied in a mild tone, rising to his feet. "That toad can try to stop us all she wants – in fact, I'm really hoping she tries. I'll turn her into a bloody popsicle and shove her off the damn Astronomy Tower. She deserves nothing less after what she did to Leo and Harry."

"Guess your pacifist days are behind you eh, brother?" Sirius grinned as he too stood up. "Good. I've been itching to give that bitch a piece of my mind."

"You're both barking," Remus sighed exasperatedly, shaking his head before he rose from his chair. "But, once a month, so am I. Let's take back Hogwarts. For our boys."

"For our boys," the Blacks nodded, smiling broadly.

Castor fought the urge to vomit as Sirius Apparated him into the centre of Hogsmeade, Remus appearing seconds later beside them with a loud 'pop'. Cas shook his head, pushing away the wave of nausea as he led the way through the village and toward the gates. As they passed the statues of winged boars, he found himself immensely grateful that it was dinner time and thus all the students and faculty would be in the Great Hall, celebrating the end of their exams and not roaming about the castle getting in his business.

If there's one thing I hate... Cas mused as they walked across the wooden bridge toward the castle. It's people getting involved in my business. He paused briefly as he detected the faint smell of blood before dismissing it as someone who had scraped their knee or perhaps busted their nose. He shook his head again to clear his thoughts before opening the double doors into the entrance hall.

He held a hand up for his companions to stop, looking around for any stragglers loitering about. When the coast was clear, he gave a wave of his hand and they moved toward the stairs at a rapid pace. They ran up the grand staircase, occasionally taking shortcuts to speed their progress on their way up to the seventh floor. They finally stopped in front of a blank stretch of wall next to which was a tapestry depicting Barnabus trying to teach trolls the ballet or something.

Castor took a deep breath before he began pacing in front of the wall, his companions following. I need to find where the diadem is hidden. He thought as he moved. The place where things are hidden. The place where secrets are buried and memories are left behind. He felt that might've been a bit much but, luckily, the Room didn't seem to think so. A wooden door appeared in front of them and they moved toward it at once.

They stood in a room the size of a large cathedral, whose high windows were sending shafts of light down upon what looked like a city with towering walls, built of what Cas knew must be objects hidden by generations of Hogwarts inhabitants. There were alleyways and roads bordered by teetering piles of broken and damaged furniture, stowed away, perhaps, to hide the evidence of mishandled magic, or else hidden by house-elves. There were thousands and thousands of books, no doubt banned or graffitied or stolen. There were winged catapults and Fanged Frisbees, some still with enough life in them to hover halfheartedly over the mountains of other forbidden items; there were chipped bottles of congealed potions, hats, jewels, cloaks; there were what looked like dragon eggshells, corked bottles whose contents still shimmered evilly, several rusting swords, and a heavy, bloodstained axe.

Cas led the way through the mountains of treasure and rubbish, lighting his wand as he did so and noting that his companions did the same. They turned right past an enormous stuffed troll, walked on a short way, took a left at the broken Vanishing Cabinet, and finally paused beside a large cupboard that seemed to have had acid thrown at its blistered surface. He looked around, spotting a very tarnished tiara that looked just like the one he had seen in the Founders' book.

He picked it up, showing it to his companions and smiling triumphantly. There were soft cheers before looks of excitement settled over all of their faces. There was only one Horcrux left to find now. Ravenclaw's diadem... bit out of place now that I really think about it. Castor mused as they walked back toward the door. The other stuff was related to Slytherin, so why Ravenclaw's diadem? He frowned as a thought occurred to him. Unless it wasn't just Slytherin's stuff he was planning on making Horcruxes out of? Maybe he was looking for objects from all the Founders? In that case -

BOOM!

Castor, Remus, and Sirius all fell to the ground as the whole castle shook. Mountains of books and miscellaneous objects rained down upon them. Cas had to roll out of the way as what appeared to be a broken Bludger slammed onto the ground where his head had once been. He threw out his left hand, forming a dome of ice over him and his brothers. Objects continued to rain down, slamming against his shield relentlessly until it was completely covered and they were buried under a mountain of rubbish.

"You two all right?" Cas asked, glancing on either side of him.

"Define 'all right'," Sirius grumbled, sitting up and rubbing his back. "Ow... I think my bruises have bruises."

"Think we're okay, Cas," Remus panted as he too sat up. "What I want to know is what just happened."

"Sounded like something really big hit the castle," Sirius frowned as he pulled himself closer to his twin. "But what? Was it an accident, or are we under attack?"

"Only one way to find out," Cas replied grimly.

He expanded his dome, raising it higher so they could stand before lengthening it, giving them a clear path to reach the door as it pushed all the objects aside. Castor stuffed the diadem in a pocket of his robes, tapping it with his wand and sealing it so it wouldn't fall out. They reached the door without incident just as another loud boom shook the castle again.

The three exchanged a look before running down the stairs, taking them two at a time before they eventually reached the entrance hall, where many students were shrieking in terror or crying. Some were trying to run up the stairs, perhaps to take shelter in their dormitories or wherever else they thought might be safe. They pushed their way through the crowd, moving toward the Great Hall. Once they reached it, they had to stop and stare in shock.

One of the walls had a giant circular hole in it. Judging by the giant boulder in the middle of the hall, Cas assumed that was the cause. He grimaced slightly when he saw arms and legs sticking out lifelessly beneath the rock before tearing his gaze away to look around the Hall. He spotted the familiar form of Minerva McGonagall standing with the rest of the professors as they levitated the boulder and used it to block the hole in the wall. He ran over to her, his family following him. She stared at them in surprise.

"Castor? Sirius? Remus? What're you doing here -?"

"No time for that now, Minnie," Cas replied, waving his hand dismissively. "What's going on?"

"Giants," said the squeaky voice of Flitwick. "They're attacking the castle."

"Not just giants," said the yellow-eyed Madam Hooch, staring out the window with her eyes narrowed. "It looks like they've got dementors, trolls, hags -"

"So pretty much all our nightmares are striding up the front lawn to kill us?" Sirius clarified. "Well, that's lovely."

"But why make their move now?" Remus frowned. "What do they have to gain by attacking Hogwarts at this moment?"

"We can question the whys later – when we survive this," Cas said briskly. "For now, we have to make sure the students are safe and the castle is defended."

"I presume you have a plan, Castor?" McGonagall questioned with a raised eyebrow.

"Put the students in the dungeons – it's underground and safe from the giant's assault," Cas replied at once. "Have Filch and Snape take them down there. Have someone seal off the fireplaces – we don't need anyone communicating with the enemy or people spontaneously popping into the castle."

He took a deep breath.

"Send out Patronuses – gather the Order, Dumbledore, everyone you can. Have them Apparate into Honeydukes cellar." He turned to look at Remus and Sirius. "Take the passage there and get them to the castle. Once that's done, barricade or blow up the passage so the enemy can't come in that way."

He turned back to the professors.

"Seal off every entrance except the bridge. We'll bottle-neck them and push them back. We keep them out of the castle and away from the students. Once you're done with your jobs, meet me in the courtyard. I'll need all the help I can get to push them back. Any questions?"

Everyone shook their heads before they took off to do as he had ordered. Cas took a deep breath before running back into the entrance hall, scanning over all the faces. No sign of Leo, Harry, or Draco but... if I know Leo as well as I think I do, he's probably run out to confront them and dragged the others along with him. Cas shook his head and cursed under his breath as he ran toward the oak front doors. Much as he loved his son and admired his unwavering bravery and loyalty, the boy could be very stupid and reckless.

He barged through the doors, immediately firing off spells as a couple of Death Eaters ran through the courtyard towards him. He disarmed them quickly before levitating them into the air and using them to push through the crowd making its way across the bridge toward him. He blasted them through the crowd, creating a brief pathway before the Death Eaters closed ranks and he was met with a giant block of masks. Cas levelled his wand at them.

"I'll give you one chance," he told them. "Leave now while you still can or I will be forced to use lethal measures to make you leave."

"You've gone round the bend, Black!" one of the Death Eaters laughed. "You're outnumbered! Even someone as strong as you can't hope to beat all of us!"

Castor paused to consider this.

"True," he conceded. "But I can do this – Glacius!"

He created a wall of ice between him and his enemies before pushing it forward. He watched with grim satisfaction as they scrambled over each other to get away before they were crushed between their fellows and the ice wall. Eventually, they were all forced onto the grounds, where they all raised their wands and began firing at the wall.

I didn't see Leo and the others... they can't be dead. The Death Eaters would be bragging about it. They weren't in the entrance hall or crushed under the boulder. They wouldn't have run from a fight so – He paused as a sudden thought occurred to him. Unless they're not in the castle. But if they're not in the castle, where would they – His thoughts cut off again as he groaned loudly. Dammit, Harry. Please tell me Voldemort didn't succeed. Please tell me you're not in the Hall of Prophecy.

Minutes ticked by wherein Cas had to lower his barrier before the upkeep burned through too much of his strength. Luckily by that point, the teachers had arrived. Shortly following them were members of the Order, trickling in as they made their way through the Honeydukes passage, down the stairs, out the courtyard and across the bridge toward them. They managed to hold the line there, keeping the Death Eaters and their army of Dark creatures at bay with Patronus Charms and various shielding and repelling spells. Unfortunately, while the numbers for the defenders of Hogwarts swelled, so too did the numbers of their foes.

Ugly old warty hags threw vials of poison at them. Inferius crawled through the crowd and tried to attack them – and Castor, who had been momentarily frozen in place by terror, had his life saved by Sirius. Vampires swarmed toward them, trying to sink their fangs into their prey but finding themselves repelled by numerous fire spells. Trolls clobbered everything in sight before the Death Eaters directed them to their enemy and they charged wildly at them. Giants continued to lob boulders at them that were blown up by various explosive spells.

They were beginning to be pushed back when a flash of fire appeared before them. From that fire came Dumbledore – his wand raised and his usually gentle expression fierce and angry. For the first time in as long as he could remember, Cas was glad to see him. Renewed energy flooded through him as he and his comrades pushed forward toward their enemies and were relieved to see them running away and scattering down toward the forest where they stood, silently waiting.

"Minerva," Dumbledore said, interrupting the cold silence. "The students – are they safe?"

"A few died in the initial attack," Minnie replied, her voice containing only the barest traces of a tremble. "And there are a few missing. Potter and his friends for one -"

"What?" Sirius said sharply, looking up from where he was currently trying to bandage his bleeding arm. "Where are they?"

"My guess is the Hall of Prophecy," Castor answered, spitting blood from his mouth as he rubbed his busted lip. "Voldemort must've finally tricked him into going. Reckon Leo and the others went too to back him up -"

"Then we have to go after them," Remus said at once. "They're walking into a trap -"

"Obviously - and so did we," Cas scowled down the lawn. "Voldemort sent his army here to keep us occupied. While we're busy here, they're getting the prophecy and trying to kill Harry and Leo in one fell swoop. They know we can't go after them – we'd leave Hogwarts open and defenceless. We don't have any choice but to stay here."

"What are you suggesting we do then, Castor?" Dumbledore questioned with a raised eyebrow. "We leave Harry and his friends to their fate? The Castor I knew would've risked everything and everyone for his family -"

"Don't question my commitment to my family, Albus," Castor growled lowly. "There are no good options here... But I have faith. The boys are strong – they won't be taken down easily. They'll put up one hell of a fight and come out of it all right, you'll see."

No sooner were the words out of his mouth than they heard the rapid approach of footsteps behind them. The Weasleys turned, their wands raised before they cried with shock. Cas turned his head to see that it was Ginny Weasley. She was bruised, bleeding, and appeared to have been crying profusely. She hugged her parents tightly and sobbed harder. Cas narrowed his eyes and concentrated, gently probing her mind.

He saw flashes of the Department of Mysteries, Hermione was injured and she went with Neville Longbottom and Luna Lovegood to take her to Grimmauld to rest up. Luna and Neville flew off back to Hogwarts and Ginny looked after Hermione until Draco Portkeyed in with her brother, Ron, as well as Leo and... Harry. Leo was cradling Harry in his arms and sobbing loudly in anguish as he clutched his cousin's limp form. Draco ran toward Ginny as she screamed and told her that Luna had the prophecy and to go back to Hogwarts and tell everyone what happened. He turned a Galleon into a Portkey and handed it to her. She landed in the entrance hall and came running toward them when she heard the sound of fighting.

Cas pulled his mind away with a small frown. Harry... are you really dead? That Horcrux should've died before you did... And Leo... I'm so sorry, son. I should've been there for you but I failed you... He shook his head before turning resolutely to Dumbledore.

"They're fine," he informed the man. "Luna Lovegood and Neville Longbottom are on their way here with the prophecy. Ron, Hermione, Leo, Draco, and – and Harry are at Grimmauld recuperating from their adventure. It's only a matter of time before Voldemort comes here to get the prophecy and brings the rest of his army with him -"

"Why, because this isn't enough?" Sirius snorted.

"If that's the case, I doubt we can hold them here for much longer," Remus frowned, looking down the grounds. "Even with you, Dumbledore, and everyone else. We're too outnumbered."

Cas frowned, looking upward at the Astronomy Tower thoughtfully.

"We only need to hold the grounds until Luna and Neville get here," he told them. "Once that's done, I can erect a barrier to keep them out and keep us in. But I'll need time. Oh, and I'll need to borrow your phoenix for a bit, Albus."

"How much time do you require?" Dumbledore inquired.

"As much as you can give me. It'll take all of my power and concentration to create a barrier that big. I'll need to draw on the Order's magic to bolster my strength – which means you'll be on your own... But, hey, it's all for the Greater Good, right?"

"... For the Greater Good," Dumbledore nodded before striding down the lawn for the last time.

He paused suddenly to look at Castor, a thoughtful expression on his face.

"Before I go, I need one last favour from you, Castor..."