I haven't had a huge amount of time to proof read this chapter so if you guys find any embarrassing mistakes, let me know and I'll fix them!
Hope you enjoy.

Chapter twenty seven

Possession

When Remus reached McGonagall's office at the top of the staircase, he did not expect to find an out and out shouting match between Severus Snape and the portrait of Albus Dumbledore. He could not recall a time he'd ever heard Dumbledore bellow at the top of his voice. It was a very odd experience.
He rested his hand on the doorknob for a few moments, ear pressed to the wood of the door.

'We need to get him out of the school,' Snape was shouting. 'He's going to be dangerous now – this is the time Albus.'

'You are wrong, Severus. We still have time.'

'What are you stalling for?' Snape said, lowering his voice. 'I can't possibly fathom why you'd want to risk everyone's safety by keeping him here. I'm doing it tonight, Albus. You cannot stop me.'

'You are still needed here,' Dumbledore said forcefully. 'It is not your time yet.'

'How can you possibly know what?' Snape replied.

'The events that are going to occur next…they have to happen. This has to happen Severus. If we ever stand a chance of restoring the wizarding world – we must allow Sirius to be possessed by Voldemort.'

Remus' heart froze in his chest. His ribs felt as though they were constricting around him. What on earth was Dumbledore talking about? Luckily, Snape echoed his sentiments.

'What on earth are you talking about?' he snapped.

'All will become clear soon enough.'

Remus, fuelled by a furious need to know what asinine plan Dumbledore had concocted this time, forced the door open with a swift kick.

'You both have some serious explaining to do,' he said harshly, his hand instinctively winding around his wand. 'Sirius is going to be possessed? How can that possibly be so?'

Snape was staring at Remus with a look of complete shock on his face.

'You left Potter alone with Black?' he said, cutting across Remus.

Remus frowned at him before suddenly realising what Snape was getting at.

'You idiot. Black is going to be possessed by Voldemort!' Snape growled. 'That's the reason why he's returned. Voldemort forced his body back from beyond the veil by possessing it!'

The words came like a smack in the face for Remus.

'AND YOU DIDN'T THINK TO TELL US THAT?' he bellowed. He pulled his wand quickly and cast a ferocious stunning spell at Snape. Snape blocked it quickly but the force knocked him backwards a few steps.

'YOU TWO HAVE BEEN CONSPIRING TOGETHER BEHIND OUR BACKS!' Remus went on. 'YOU'RE GOING TO GET SOMEONE KILLED!'
He turned to face Dumbledore's portrait. 'Again and again you risk Harry's life by keeping him in the dark. And now you wish to keep Sirius here where innocent people could be killed? What is the matter with you!'

He ran towards the office door, his wand still firmly in his hand. Snape was suddenly by his side.

'No more, Albus,' Snape said darkly. 'From now on, you have no say in what we do or how we do it.'

They shut the door loudly behind them and for a moment the two men stared at each other at the top of the staircase.

'Does Sirius know?' Remus asked bluntly.

'He does.'

'Does he know he has to return to the veil?'

Snape nodded. 'He does. Do not fear, Lupin. I have a plan.'

Overhearing the snippet of conversation, Remus had already worked out what Snape was planning to do.

'You're taking him back?' Remus asked.

Snape gave another swift nod and then began his descent down the staircase. 'A dead body cannot die again,' he shouted behind him. Remus raced to catch up.

'You can't let Harry be the one,' Remus said behind him. 'You know he'd want to do it.'

'Like I said, Lupin,' Snape told him again. 'I have a plan. Go and find Potter, there is something I must tend to here.'

'It's so weird,' Harry said to Sirius, having worked up the courage to sit beside him on the bed. 'I can almost see right through you.'

He reached out and poked Sirius hard on the bicep. 'Can't you feel that?' he asked.

Sirius shook his head. 'I can't feel anything,' he said. 'And Snape keeps bringing food back from the Great Hall. It's driving me nuts.'

'You can't eat either?' Harry said, astounded. 'That must really suck.'

Sirius laughed quietly. 'It really does.'

Harry checked the clock on the wall opposite. 'I should get going,' he said. 'Remus was only meant to be stalling Snape…' He got to his feet awkwardly. 'I'm going to speak to him, Sirius. We'll find a way to get you back without Snape having to sacrifice himself. Okay?'

Sirius smiled at him sadly. 'I always admired your optimism, Harry,' he said. 'But if Snape is willing to do this, then why not let him?'

'Because there might be another way!' Harry yelled. 'I'm not just going to let him throw himself off a bridge with you in tow. We'll work this out together.'

Sirius gave a noncommittal shrug, obviously dubious that there was a resolution to this. He lifted his gaze to meet Harry's and, for the briefest moment, Harry saw a flash of red dart across his ghostly irises. Panic ripped through him instantly. How could he have been so stupid? Sirius had told him himself that Voldemort had possessed his body… of course he was going to make himself present at some point, especially if Harry was around. And Harry had seen the signs enough times in himself over the summer. Sirius looked at him curiously.

'What?' he asked, frowning. He hadn't seemed to notice…

'N-nothing,' Harry said, stepping backwards. 'I need to go.'

Another red flash, stronger this time and Sirius clapped a hand to his head, wincing slightly. Realisation hit him hard and his eyes shot open, wide and terrified.

'Harry,' he croaked. 'You have to get out of here.'

'If I leave, you'll follow me,' Harry said. 'There are hundreds of students out there.'

'Don't be an idiot!' Sirius roared, swiping at several glass bottles on Snape's side. They fell to the ground with a crash. Harry sidestepped the leaking fluids as they steamed and bubbled through the ground.

'There is a way to fight it,' Harry said. 'You can hold him off.'

'I can't,' Sirius said desperately. 'This is just a body – there is no soul left inside me to fight. There's only him.'

Another flash of red and Sirius let out an odd feral cry. His limbs became stiff and taught as if he had no control over how they were behaving.

'Sirius –' Harry said sadly, his back up against the door. 'Please.'

Sirius managed to peel his eyes open for a few moments. His body trembled from the effort of restraining Voldemort for a few moments longer. He looked Harry in the eye.

'I'm sorry,' he said. 'For whatever happens after this – I'm sorry.'

There was an awful cracking sound that followed. Harry instinctively clamped his hands to his ears. Sirius' body arched backwards so far that Harry thought it was going to split in two. He stared back, horrified, as Sirius writhed and convulsed furiously. His legs trembled beneath him; his arms shook and contracted painfully. The ghost like flesh on his arm began to bubble and move eerily, as though there were worms wriggling beneath it. Harry stared, completely transfixed. Slowly, painfully, the image of the Dark Mark etched its way onto Sirius' clear arm, burning its way into existence. It was accompanied by a heart rendering cry from Sirius. Harry wanted to run forward and hug him, tell him everything was going to be okay and that he could fight this. But there was nothing he could do. Voldemort had won, again.

The last few lines of ink slithered their way onto his skin. The Dark Mark stood out in all its glory, thick and black and hissing softly as Voldemort breathed life into it once more. Harry's hand reached for the door handle; his fingers fumbled on the brass handle. Sirius breathed a heavy sigh and opened his eyes once more. Fiery red glared back at Harry from across the room. A terrible smirk grew across his face, one that certainly didn't belong to Sirius.

'And so we meet again, Potter,' Voldemort hissed through Sirius' teeth. 'I wasn't expecting to see you so soon.'

'I won't let you use his body,' Harry said. 'I will finish this.'

Sirius lifted a puppet like hand towards his arm, his fingers dancing delicately over the Dark Mark. Harry drew in a breath, eyes wide with anticipation.

'How exactly do you plan to do that when my Death Eaters have over run the castle?'

'You wouldn't,' Harry pleaded. 'They're not your Death Eaters anymore. They're their own organisation! Let it go! Your time here is over!'

'NOT IF I HAVE MY WAY!' Voldemort bellowed. 'They will make you suffer, Potter. For all the times you have defied and thwarted me -they will make you pay!'

His fingers stopped dancing and he pushed down hard in the centre of the Dark Mark. A loud screech echoed around Snape's chambers and Harry winced, throwing his hands up to his ears again.

'Please! See reason!' Harry yelled over the noise. 'You can't cast magic, surely. You'll have no power over them!'

'There is more to power than waving your wand, Potter,' Voldemort sneered. 'I have seen the power of the veil, the power of life and death itself. This body was just a starting point – I can move on to another wizard and take his magic for my own!'

Voldemort's hard, red eyes burned into his own. The hairs on the back of Harry's neck stood up and he took the opportunity to wrench open the door and lock it quickly behind him. He could hear Voldemort screaming the other side, battering it madly with his fists. It wasn't going to hold long. Harry took several deep breaths. Things couldn't get much worse than this surely. A raving mad Voldemort possessing Sirius Blacks body and a whole load of Death Eaters on their way to the castle. How the hell were they going to get out of this one?

'Harry?' Remus' out of breath voice came from behind him. Harry spun around and Remus took one look at him before skidding to a halt and saying,

'Oh no.'

Harry nodded quickly. 'He's possessed.'

'I know.'

'By Voldemort.'

'I know.'

'And he's just called his Death Eaters. They're coming to the castle.'

Remus took a few seconds to be shocked by this and then quickly shook some sense into himself.

'Run and tell Severus. He's in the McGonagall's office. I'll rally the teachers and the Order. We need to evacuate the school.'

'We're not going to fight?' Harry said.

'We're not prepared. Voldemort has control of Sirius and he's inside the castle. We need to get everyone out… Go, Harry. Now!'