Author Notes – Sorry again for the long delay, I've been excessively busy recently, but hopefully the next chapter will be uploaded more quickly. Quite a lot of exposition in this chapter, but we're not about three quarters of the way through the story, so thanks for staying with it.

Rating – PG.

Note – I do not own Harry Potter or any of the characters, that privilege belongs to JK Rowling.

CHAPTER EIGHTEEN

Hammer into Anvil.

Slytherin found Merlin sitting alone in one of the many classrooms. The room was lit by just a single candle, and the long shadows cast on Merlin's face barely disguised how haggard his features had become in the last few days. He had been brooding like this for many hours now, having declared that he needed some time to think. Arranged on the desk before him was the chessboard that he carried round everywhere, the pieces all in position. Slytherin was a master of the game, but that was hardly necessary to realise the simple truth, that Merlin was losing the game. As every move went by, his old friend became more worried, slept less, and spent more time on his own, staring at the board in the half-darkness.

Merlin gave no sign that he had heard Slytherin enter the room, until Slytherin cleared his throat, slightly more theatrically than was necessary. Merlin jumped slightly, and looked up. His face momentarily lightened for a moment, and then his frown descended once more and he went back to staring at the chessboard. He reached out with his right hand and gripped the top of his remaining bishop. Several moments passed where he remained completely frozen in place, before gently sliding the bishop three squares diagonally to the north-east, bringing it much closer to the white king. He kept his hand on the piece for a few moments, and then moved the bishop back to its original position, his frown becoming even more pronounced.

'Get a grip,' he muttered to himself. 'White bishop...black knight...checkmate is seven moves by the look of it...unless I take his queen.'

Slytherin tried clearly his throat once again, but this time Merlin ignored him completely. Slytherin sighed and left the classroom once more. As he closed the door behind him, he came face to face with Gryffindor.

'Coming to see our dear friend?' asked Slytherin, and Gryffindor nodded. 'Well, I've just tried that, and he's being very unresponsive. Not surprising really.'

'What do you mean by that?' said Gryffindor, running his hand over the carved wooden door, as if deciding whether he dared to push it open. He stepped back and began to finger the hilt of his sword, which was, as always, securely placed in its scabbard and tucked into his belt.

'Come on Godric,' replied Slytherin, a small smile playing across his lips. 'Surely even you must have realised. He's losing the game. He knows it himself, mate in seven moves I think I heard him mutter. It's very nearly over.'

'You should have more faith my friend,' said Gryffindor. 'Merlin has never yet failed. He will think of something. There is no other way.'

'I suppose you are right, especially since that creature, whatever it is, has blocked all the exists from the castle. It left a threatening message that anyone attempting to leave the grounds of the castle would be killed.'

There was a sudden crashing sound from inside the classroom. They looked at each other, before Gryffindor bolted open the door and they both hurried inside. Merlin was on his feet, and the chessboard was now several feet away on the ground, several pieces having shattered on impact. It was clear that Merlin had thrown the board across the room. As they watched, the pieces reformed, the board raised itself slowly into the air and glided silently across the room before it came to rest exactly where it had been before, with the pieces all reassembled and back in place.

Merlin sighed and sat down once more. A moment later, he looked over at Gryffindor and Slytherin who were both watching him silently. 'Sit down won't you gentlemen?' They moved together, crossing the room and sitting in the two chairs placed opposite Merlin.

'The game isn't going very well,' continued Merlin, a fact that Slytherin considered to be blindingly obvious considering Merlin's attempt to break the chess board. 'Every time I come up with a plan, he seems to second guess me and moves to counter it. He's slowly wearing me down.' He gestured to the pieces that were set aside at either end of the board, there were rather more black than white ones.

'I don't understand why you're playing black anyway,' said Gryffindor. 'Surely black is the colour of evil.'

Merlin waved his hand impatiently. 'Spare me your simplistic notions of good and evil,' he said dismissively. He reached forward again and moved one of his knights. 'There, a little unorthodox perhaps, but it might throw him off his game a little.'

'While you're here Merlin,' said Slytherin, deciding to take advantage of this opening in the conversation. 'I think it's about time you told exactly who it is you're playing against. We have been very patient, doing everything that you have asked, but I think you owe it to those who have died to tell us exactly what is going on.'

Merlin raised a finger to his lips, and Slytherin felt the temperature in the room drop a considerable amount. 'He's coming,' Merlin whispered, and Slytherin felt the hair on the back of his neck stand up for the first time in a long while.

The dark shadow emerged from the gloom, this time it appeared as though it was coming from the ground itself. It swirled around their heads, and a terrific wind blew up, causing Slytherin and Gryffindor to stagger backward slightly. Merlin, however, kept his feet planted firmly on the ground, and seemed immovable in the face of this force of nature. 'He does this every time,' Merlin explained. 'Trying to spook me I think.'

After a few seconds, the wind died down again, and the shadow reformed as the same old man that had appeared beside the lake all those days ago. It felt an age since that terrible night, Slytherin thought. Having to talk to and comfort the families of those who had been killed had taken up much of his time since then, but this had only strengthened his resolve to see this thing, whatever it was, defeated. The urge to reach for his wand was almost overpowering, but he restrained himself, remembering what had happened the last time.

The old man walked slowly over the board, and looked down at him. Checkmate in seven moves. Once again, the voice seemed to come from the air itself, and was followed by an evil cackle that filled the room. The old man reached out a withered hand, and grasped one of the white rooks, moving it three spaces to the left. You have three hours to make your next move. He dissolved once more into black shadow and vanished from the room.

Merlin looked down at the board once more. 'He did see that coming then,' he muttered, and sank once again into his chair, staring darkly at the candle, which amazingly had not gone out when the strong wind had blown through the room.

Gryffindor and Slytherin looked at each other again. 'We'll leave you to the game,' said Slytherin, and he and Gryffindor left the room as quietly as they could. 'We need to start planning for what we do if he loses.'

'If?' said Gryffindor. 'I think you're being too generous. We need to start bolstering the castle's defences now. The way things are going, this game's going to be over by tomorrow night. And then we don't know what's going to happen.'

'Did you try again?' asked Slytherin, as Gryffindor and Hufflepuff came striding in through the double doors in the Entrance Hall.

'We did,' said Hufflepuff gravely, pocketing her wand. 'And it's the same for every spell we try and cast. It just dissipates as soon as we cast it. That thing is stopping us from shoring up the defences around the castle. It wants us as vulnerable as possible.'

'That settles it then,' said Slytherin. 'That means that if Merlin loses, that thing and its servants will attack the castle, and considering what they did to the Great Hall, I'm not sure what we can do.'

'Have you spoken to Merlin today?' asked Gryffindor, as the three of them began to climb the Grand Staircase. 'He should be made aware of the defensive situation.'

'He ordered the library emptied this morning, and has been in there ever since. He's been trying to find a way of not losing the game in the next three moves. Let's just say he's not getting very far and it's annoying him.'

They walked in silence for several minutes until they reached the library. It was dusk now, and the setting sun was streaming through one of the windows, casting light on Merlin's face; he looked more tired than ever, he had dark bags under his eyes, and his brown hair was increasingly unkempt. His white hat was placed beside the chessboard on the desk. One glance at the board told Slytherin all he needed to know; the white queen and one of the white rooks was closing in on the black king, and looked set to checkmate soon.

'No, no, that's not right,' said Merlin, as he moved his pawns back and forth across the board, as though desperately searching for a way out. 'Think, come on now.'

Hufflepuff moved over to the window and looked down into the grounds, seemingly enjoying the sun on her face. But Slytherin could tell that she was frightened for her students. Without any extra defences, they would stand no chance against those creatures. Slytherin looked at Merlin closely; although his face did not betray it, Slytherin knew that he too was scared.

It was at that moment that Slytherin spotted what was also on the desk, a small stone flask that looked very old, and completely out of place at Hogwarts. From his travels, it looked like the sort of object they would possess in the Nordic countries. He cleared his throat and said, 'What's that Merlin?' while pointing at the flask.

Merlin looked up and then glanced down at the flask. 'Just an idea,' he muttered, before scooping it up in one hand and making it seem to vanish into mid-air. 'Don't let it concern you. We have more pressing issues.' He stood up from his chair, and began to circle the desk, all the time staring at the board, as though willing it to give him the answer.

There was complete silence for several minutes, but none of them wanted to leave the room. Gryffindor, Slytherin and Merlin stared at the chessboard, while Hufflepuff continued to look out the window, perhaps hoping for some flash of inspiration. The sun continued to sink, until it was below the horizon, and the sky began to darken. Slytherin could not help thinking that that had been the last sunset that anyone in Hogwarts would see.

'You might want to come and look at this,' said Hufflepuff, breaking the silence.

'What is it?' asked Gryffindor, but Hufflepuff did not reply. Slytherin moved over to stand beside her and looked down at the grounds. There was still just enough light to make out what was happening at the edge of the Forbidden Forest. Hundreds, if not thousands, of those shade creatures were beginning to gather, standing in ranks, their blank faces staring at the castle walls. With every second that passed, more and more appeared from out of nowhere and joined the assembled group.

'It seems the party is about to start,' said Merlin at Slytherin's shoulder, who jumped, not having heard him move across the room. 'One move to go.' Slytherin looked at the board and saw that some of the pieces had moved from where they were before.

The door of the library creaked open, and the old man walked calmly into their presence, his face contorted in a terrible smile. My armies assemble, it said.

'We had noticed,' said Merlin, and he moved across the room until he was mere feet from the old man. He gestured at the board, and Slytherin could have sworn he saw a glint in his old friend's eye, something he had not seen for some time. 'One move,' continued Merlin. 'Find the winning move. Spring a trap on me...If you can.'

The old man hurried to the board, with a childlike excitement on his face, and moved the white queen one space to the north-west. Checkmate, it said, and an unholy laugh rang out like a death rattle. The old man reached forward and toppled the black king, all the while laughing maniacally. Slytherin glanced out the window once more and saw that the legions of shades were beginning to march slowly towards the castle. He turned back and was amazed to see that Merlin was smiling widely. His old friend reached out and put the black king upright again. What are you doing?

'I think you should look at the board a little more closely,' said Merlin. And then Slytherin spotted it; the black queen had moved from where it had been before, cornering the white king and placing it in check, so that the move their opponent would have made was no longer possible. Slytherin looked out of the window once again and saw that the shades had stopped advancing on Hogwarts. 'Got a little overexcited there I think,' continued Merlin, and the old man's face contorted with rage. 'Try again.'

The old man paused for just a second, and then moved his king across one space, and out of check. 'Oh dear,' said Merlin, still smiling. 'It seems that you've fallen right into my trap. You didn't really buy all that rubbish about me thinking I was going to lose did you?' The old man looked at him, and Slytherin could have sworn he saw a flash of fear cross the wizened face. Merlin moved his remaining bishop and cried 'Checkmate!' in triumph.

The old man screamed, an unearthly sound that filled the entire room. Gryffindor had his wand out in a second and shouted, 'Reducto!' The spell hit the old man, and his body shattered apart, dissolving once more into the black shadow. Merlin sprang into action; he snapped his fingers and the flask reappeared in his hand. He jumped over the desk into the cloud of darkness and muttered a few words. The cloud seemed to twist and ripple, and then was sucked inside the flask with a distant-sounding scream.

A ringing silence fell in the library. The four of them all looked each other. Slytherin glanced once more out of the window and saw that the shades had all disappeared. He breathed a huge sigh of relief; they were safe once more. Merlin was smiling broadly at him. 'Worked out pretty well I thought. Thank you for that timely intervention Godric.'

'Has that thing gone for good?' asked Hufflepuff, eying the flask wearily.

Merlin held out the ornament in front of him. 'Trapped in here as long as the flask holds its integrity. I suggest that you put it somewhere dark and dangerous where no one will ever find it. Do you think you could manage to find such a place Salazar?'

Merlin looked at him and Slytherin felt strangely inadequate under the piercing gaze of his brown eyes. 'I think I should be able to,' he said, and an understanding passed between the two of them. Merlin handed him the flask, it felt strangely heavy, and he could feel a faint vibration within the stone itself. He looked up at Merlin, who had his white hat perched back on his head, and looked set to leave. 'Goodbye Merlin.'

'Goodbye Salazar,' said Merlin, and he turned towards the library door. 'Make your choices wisely, history will remember them whether you like it or not.' And with that, he was gone. Slytherin stared at the place where he had disappeared for a moment, thinking about the future and the choices that he would soon be making. In the back of his head, he knew that he would never see his old friend again.

Nearly a thousand years after the events of those few days, Albus Dumbledore was sitting in his office, examining his golden pocket watch as the small planets moved around the face. He was waiting for a visitor, who was uncharacteristically late. He sighed and placed the pocket watch back inside his robes and stared intently at the fire. It had taken some considerable effort to join the fire to the Floo network without a lot of complicated questions. Dumbledore leaned back in his chair and looked out the window; it was a beautiful August day and the castle grounds were blooming with life. At times like this, he missed having the students there, he knew the affection they all felt for the castle and on days like this, it was never more beautiful. It always reminded him of why he never liked to leave.

The fire suddenly crackled into life, and a short man wearing a white linen suit emerged from it, dusting ash from his clothes. He removed his white fedora hat, and blew hard to remove the remaining dirt, creating a cloud of dust that swirled around the office. Dumbledore coughed lightly as Merlin finished dusting himself off and clambered out of the grate. 'And when exactly did you lot think travelling between fireplaces was a good idea?' he asked.

'The Floo network has been in operation for nearly fifty years now Merlin, you can hardly failed to have noticed it before.'

'Clearly I've been away too long,' retorted Merlin, taking the seat opposite Dumbledore's desk. 'You've all gone mad in my absence.' He paused, and smiled. 'It's good to see you Albus, exactly how long has it been?'

'Nearly sixty years Merlin,' replied Dumbledore, his eyes twinkling. 'And I must say you have missed some eventful times.' Merlin raised his eyebrows. 'Plenty of time for all that later. For the time being I require your help.'

'Oh yes?' said Merlin. 'Well this must be a new record for small talk. We managed to go less than twenty seconds. "Nice to see you Merlin, but here's what I need you to do" routine.'

'You wouldn't have it any other way,' replied Dumbledore. 'Now listen to me carefully. For some time I've felt this unease within the castle I can't quite put my finger on. The idea that there's something terrible going to happen. There's a power emanating from somewhere within Hogwarts, and recently I remembered the story you told me a very long time ago, about what happened here when the four Great Ones ruled this place. The story of the shades, and the dark power that tried to destroy this place.'

'And what made you think of this particular story?' asked Merlin, clearly intrigued.

'That sense of a building power, I felt it incredibly strongly the other day when I was walking along the first floor corridor, passed a particular disused bathroom.'

'And the significance of this bathroom is?'

'It's the entrance to the Chamber of Secrets.' Merlin stood up quickly, and began to pace the office. Dumbledore waited for a second before continuing. 'You made Slytherin seal that creature inside the Chamber didn't you?' Merlin paused, looked at Dumbledore, and nodded. 'I don't know whether what I fear has happened has indeed happened, but I need you with me to go and find out.'

Merlin stopped pacing the room and looked into the fire, which was still crackling merrily in the grate. Dumbledore watched him carefully, he was clearly thinking hard. 'Very well,' said Merlin in the end. 'Take me to the Chamber. I only hope to God that you're wrong.'

They walked in silence to the first floor. 'What a terrible mess,' said Merlin as they entered the disused bathroom. 'Don't you ever think about cleaning the place up?'

'I'll certainly pass the suggestion on to Mr Filch,' said Dumbledore with a small smile. 'Now then, the entrance to the Chamber is here. You see that snake engraved on the tap other there, that's where we go in. If you wouldn't mind doing the honours.'

'As you wish,' said Merlin, stepping forward to stare at the snake. A low hiss escaped from his mouth, and the sink began to drop away, revealing the entrance to the Chamber of Secrets. Dumbledore walked towards the hole in the ground and looked down. 'Hardly the most comfortable of entrances it seems,' continued Merlin, moving forward to join him.

'Indeed not,' said Dumbledore. 'Oh well, if needs must.' And he jumped into the hole and disappeared from sight, swiftly followed by Merlin. Dumbledore felt himself descending down the stone slide. He had never actually ventured into the Chamber before, even though he had known its location for more than a year; it seemed as though there were dark secrets and memories down here that it seemed better not to disturb. How right he had been.

'Now then,' said Merlin, snapping his fingers, creating a ball of light that he tossed into the air. 'We're looking for a broken flask, ninth century Scandinavian design I reckon.'

'Well that shouldn't take more than a few weeks to search this place,' said Dumbledore, and Merlin rolled his eyes. 'Oh very well, let's get started then shall we?'

In the end it did not take them long to locate the flask. 'I think this might be what you're looking for!' called Dumbledore, and Merlin rushed over to join him. Lying on the floor beside a large pile of rocks was the broken flask that Merlin had used to trap the creature over a thousand years ago. 'Oh dear, it looks like my suspicions were correct.'

The great wind blew up around them, just as it had once done to the founders of Hogwarts. From out of the rock face came the dark cloud, that swirled around their heads. Both Dumbledore and Merlin watched it with expressions of complete calm on their faces, the creature must have known that these two were not easily intimidated. Eventually it settled back into the form of the old man that had appeared all those centuries ago.

I knew that you would return, it said to Merlin. It was only a matter of time before you noticed my escape. So...we play the game again.

'I have no time for your games,' said Merlin dismissively, as Dumbledore watched the discussion apprehensively, keeping one hand clasped firmly on his wand. 'I beat you once, I'm in no mood for a rematch.'

You have no choice wizard, the pieces are already assembled. There was another gust of wind, and another black cloud appeared from the rock and formed itself into the shape of a chessboard. Only this time the game will be for higher stakes. The lives of my shades, against the lives of your wizards.

Dumbledore stepped forward. 'I have a question,' he said calmly. The old man's face twisted somewhat at this interruption, but the creature did not say anything. 'You've been living in my castle, rent-free I might add, for some time, so I think it's only fair that you tell me exactly who or what you are.'

'I think I can field this question,' said Merlin. 'If you will allow me too.' The creature once again said nothing, so Merlin continued. 'Long ago, before the creation of the Ministry of Magic, and before the guidelines were set down detailing exactly what wizards were permitted to do, the Ancient Ones engaged in all kinds of terrible experiments. They wanted to create more and more powerful spells, but the side effects of these became ever more dangerous and the results more unpredictable.

'One such experiment, which occurred around the end of the ninth century, involved the creation of a sentient spell, one more intelligent and more powerful than any other weapon, that could be used to destroy the Ancient Ones' enemies. The spell they created stands before us today; it has the ability to manipulate the world around it, and create physical manifestations of its consciousness, which are the shades that it referred to.'

'I see,' said Dumbledore. 'So the Ancient Ones created you in order to destroy their enemies. Let me guess, you turned on your creators and destroyed them.'

'Indeed,' replied Merlin. 'But the Ancient Ones prepared for such an eventuality; they built into the spell a way of subduing it, by proving oneself more intelligent than it. They calculated that together they would be able to outsmart the intelligence they had created. This challenge would manifest itself in a simple game. A game of Gods.'

'Chess,' finished Dumbledore simply. 'And now it's broken free of the trap you put it in, and it wants to play the game again.'

'Only this time, it's upped the stakes. Instead of a simple game, it has decided to involve real people. That makes my job so much harder than last time. Not only do I have to beat it, I also have to control and manipulate my own pieces.' This made Dumbledore raise his eyebrows. 'Unfortunately we have little choice. If I lose the game, this creature can do whatever it wants to us and the castle.'

Enough, it said, its voice reverberating off the walls of the Chamber. The game begins. Take your first move wizard, I will be waiting for you. The old man dissolved once more into black shadow and disappeared into the rock face. A small scroll of parchment fluttered to the ground. Merlin bent down and picked it up.

'What is it?' asked Dumbledore, his interest piqued.

'Oh dear, oh dear,' replied Merlin, handing it to Dumbledore. 'It's a list of my pieces.' Dumbledore glanced down the list and his heart sank. It would be him, he thought, it was always going to be him. At the bottom of the roll of parchment were written the words, in clear black ink, "King: Harry Potter".

'That,' said Cedric, as Merlin finished speaking. 'Was the most fantastic story I've ever heard.' He looked sideways at Harry for some clue as to what he was thinking, but his boyfriend's face remained largely impassive. 'So, you're saying that we're both chess pieces in a giant game between you and this whatever-it-is.'

'Indeed yes,' replied Merlin. 'And I'm truly sorry about that. Believe me, I don't want to manipulate people to where I need them to be, but the consequences of not doing so would be so much worse. I've had to make some terrible sacrifices.'

Harry was still staring at Merlin without speaking, and his silence was beginning to unnerve Cedric. Normally Harry would have been full of questions. Eventually he broke his silence. 'How much manipulation?' he asked quietly. Merlin looked at him puzzled, as if he had not heard properly. 'How much did you manipulate your pieces?'

'Mostly just their physical locations, getting them to where I needed them to be. Positioning them to fight the shades when required. Although...' He paused for a moment and looked sideways at Dumbledore. 'In some cases I had to completely rewire their personalities.'

'You're referring to Severus I take it,' interrupted Dumbledore, his eyes twinkling. 'Surely you two must have wondered what was behind his sudden change in behaviour. Rest assured that the change is only temporary, he will return to normal when the game is over.'

Cedric did not feel particularly reassured by this, but before he could say so, Harry was speaking again. 'And how much have you manipulated us?'

Cedric could tell where Harry was going with this, and decided to intervene before Merlin could answer. 'Never mind that now, what can we do to help?'

'For the time being, keep your heads down,' replied Merlin. 'Neither of you are in any immediate danger.' Cedric snorted and gestured at his side, where the wound was still barely holding together. 'Yes, I'm sorry about that. It was a risky move on his part, and it almost worked out. Luckily I got Harry and Moody there in time to save you.'

Harry snorted. 'Is there anyone who isn't being used as one of your chess pieces?' Merlin didn't answer this question. 'What I don't understand,' continued Harry, 'is how that thing got out of the flask. Who broke it?'

'You did, Harry,' replied Merlin. Harry and Cedric both stared at him, completely lost for words. 'Well, not you exactly. Salazar hid the flask within the walls of the Chamber of Secrets itself. When you went down there nearly two years ago, and Gilderoy Lockhart caused that little earthquake, the part of the wall that collapsed contained the flask. It smashed on impact, and there you are.' He paused for a moment. 'I had that little bit of information confirmed to me not long ago. I had to take it from Gilderoy's mind, but it confirmed my suspicions. I saw in the memories, the ones he couldn't reach, the flask falling to the ground and shattering. That was when the creature escaped.'

'This is all so much to take in,' said Cedric. He could feel his head spinning trying to comprehend it all. Everything that had happened that year seemed to make sense now. 'I just can't believe it. We're being used.'

'Boys,' said Dumbledore, looking at them both with his piercing blue eyes. 'I realise this is a shock for you, but I'm asking you to trust me...and Merlin.' He saw Harry look away for a moment, his face creased with concern, but he recovered a moment later. 'If we all work together then I am convinced that we can defeat this creature once and for all, without any more lives being lost.'

Cedric and Harry looked at each other, and an understanding seemed to pass between them. They looked back at Dumbledore and Merlin and said together, 'OK.'

'Excellent,' said Merlin, clapping them both on the shoulder, and striding over to the chessboard. 'Shall we talk strategy then? Rest assured that we will keep you both informed of the progress of the game, and when you will be needed.'

About twenty minutes later, Harry and Cedric emerged from Dumbledore's office. 'What do you reckon?' asked Cedric. Merlin had explained to them his seemingly foolproof strategy, but Cedric still felt uneasy about the whole thing.

'Merlin's right,' said Harry. 'Although I still can't believe he's actually Merlin. Anyway, never mind that. Whatever our own feelings, we don't have any other choice but to play the game. You heard him, the consequences of losing are so much worse.'

'And you trust him?'

'I trust Dumbledore.'

'I just can't believe he didn't tell us about this before. He's put us both in terrible danger.' Harry frowned. 'I know, "greater good" and all that. It just makes me uncomfortable.'

'I don't like it any more than you do Cedric, but we don't have a choice.'

Cedric paused for a moment, and then decided to breach the subject. 'Earlier you were going to ask him how much he had manipulated our relationship.' Harry nodded. 'I stopped you because I don't want to know. All that matters is that I love you now.'

Harry smiled for the first time since they had entered Dumbledore's office. 'I love you too Cedric. Now come on, let's go to Gryffindor Tower.'