This is just a One-Shot that got into my head after watching Insidious and so here it is. Enjoy and remember I own neither harry Potter or Insidious, they belong to JK Rowling and Blumhouse Productions!

A bit late for a movie that came out in 2011 i know but better late than never. Anyway this was just a little idea that appeared in my brain, what would Harry Potter do if he turned up in the Insidious series. Curbstomp those Ghosts that's what!

Now I know what a ghost is. Unfinished business, that's what.

Harry James Potter was a man of many titles and positions, the Boy-Who-Lived, Man-Who-Conquered and probably the one he hated the most Master of Death.

Unlike what everyone else seemed to believe it did not, in fact, render him Immortal or grant him wealth beyond imagining as some people believed. He was walking through the quiet halls of the Black home of Number 12 Grimmauld Place.

Despite the black painted walls of the house, it was well lit as Harry moved through the corridor arriving at the door to the Library. Opening the door he smiled as he saw his little cushioned chair sitting by the fire. It was his little bit of peace and quiet.

The house, to be honest, served that same purpose. Here he could get away from his near messiah-like fame in the Wizarding World.

He was just about to sit down in his chair a book pulled from one of the shelves in his hand when the moment he was about to plant his bum on the seat he paused.

Blinking he frowned before narrowing his eyes taking a look around the room.

Something was wrong, his instincts were never wrong and they were telling him that something was really wrong.

Connecting to the Wards he checked for anyone trying to breach them, he checked for any abnormalities in the buildings defences. He found nothing.

Then a bolt of inspiration hit him as an idea for what was setting him off formed in his head. The moment his mind settled on the idea he knew he was right. It made him groan internally, if he was right then he would have to go back there he thought with disgust.

He hated that place, The Further.

The space between Heaven and Earth where spirits move through before going to rest for all eternity in the afterlife. It was a place of twisted horrors and sprits broken and fallen into madness, of those who try to cling to life even after they have passed on.

The Master of Death was more than just a title, it gave him immense power in the Further. The title was less of a claim and a right and more of a job.

It was his role to keep the spirits of the Further, those malevolent ghosts and spirits who haven't lingered in the physical realm by magic saturation in the same way the ghosts of Hogwarts were. Those ghosts had no choice but to linger, their spirits bound to the castle through magic.

No his job was to stop those sprits who tried to do what Riddle once did and return back from the grave uncaring of the harm they could cause.

Sighing he stood once more, wand in hand as he fingered the Stone hanging on a golden chain around his neck. Closing his eyes he pulled on the mental connection that had been forged with the Cloak of the Unseen Veil of the Three Hallows. He let one of the abilities granted by its power drop and he took a deep breath, he could sense it now with his magic.

The world that existed just below reality. The dimension just out of sight hidden inside, around and within normal space.

He wouldn't have even known of its existence if Luna hadn't sat him down and explained it to him soon after the Battle of Hogwarts. For she was born with the ability of Astral Projection and was able to project her spirit into The Further or at least she had been able to. Her Mother and Father were very… unique individuals even by the standards of Wizards and Witches though in this case that turned out to be a boon for they unlike many even in the Wizarding World they knew about The Further and were able to seal her ability away before she attracted the attention of too many malevolent spirits.

He himself hadn't been able to see the ghosts and spirits who inhabited this dimension at first the Cloak shielding him from the spirits and ghosts but he had known something had changed and that somehow he could see more than before.

Closing his hand around the Stone on his neck he used the power of the Resurrection Stone tearing a hole, in reality, he disappeared fading out of existence as both his spirit and body went into the Further a feat that was unique to the Master of Death.

He watched as the world fell away around him being replaced by a pure white train station.

One he was intimately familiar with.

This place was where he had met Dumbledore after he had sacrificed himself to kill Dumbledore. Unknown to him however this whitewashed world was the domain of the Master of Death within The Further and the only reason he had been able to visit it on that horrible night was because he had already become the Master of Death when the Resurrection Stone came into his possession.

He took a deep breath as he rubbed his hands together. "Alright, let's get to work."

Closing his eyes he spread his sense out, travelling through the barriers of his domain as he drew on his magic and the power of The Further, to pierce through time and space as he searched for when and where the problem was coming from. The Further was a world where time was irrelevant and time zones seeped into one another. If he wasn't careful his awareness would be scattered across everywhereanytime in this strange dimension.

There!

He opened his eyes he had found the source though he would need to hurry, they were closing in. the Elder Wand appearing in his hand he swiped it downwards in front of him tearing a hole in his domain as if it was no more difficult than tearing paper. He didn't even hesitate for a second as he stepped out into the shadowy darkness of The Further leaving the bright whitewashed King's Cross behind.

Josh Lambert gripped his son to him tighter as he held the lantern aloft with the other, his eyes scanning the pitch-black darkness of the void they had found themselves within.

It had been a harrowing and utterly bizarre time for the father of three. It had begun soon after moving into their new house when his son Dalton had slipped into an unexplained coma after falling from the attic. None of the scientists or doctors could explain how or why he had slipped into the coma.

Three months later they had brought their son home from the hospital when nothing about his condition changed. Thought that was when the supernatural attacks began to occur, his wife was even attacked by an apparition of a deranged looking man. Not even moving house stopped it.

He and his wife had grown desperate and through his mother Loraine they reached out to Elise Reiner, a woman who specialised in the investigation of Paranormal Activity. She explained Dalton's ability to them, as insane as it sounded his son had the ability to astral project, going into a place called The Further where the spirits of the dead reside before moving onto the afterlife and that a Demon from this strange realm wanted their son for nefarious proposes.

They hadn't believed her at first, who would to be honest. However, he was forced to admit the truth when he discovered Dalton's drawings for the same Demon that Elise was describing.

After that Josh discovered from his mother and Elise that he too had that ability and that he had met Elise once before in his youth when he had drawn the attention of a malevolent black dress wearing woman who was getting closer and closer to him in each photograph they took of him. Eventually, they were forced to hypnotise him to suppress his ability to astral project before she was able to possess him.

She had put him under hypnosis allowing him access to The Further, the sight of seeing his body was an incredibly strange one and the misty world was an incredibly unsettling one. However he had a duty, his son needed him and he would not disappoint him in his time of need.

He made his way through the house until he reached the attic and a strange otherworldly red door. One guarded by the man who had nearly attacked his wife in their baby's room. He was about to be overwhelmed when Elise's voice reminded him that he was alive and stronger than the deranged dead man.

The lair of the Demon had been dank, dark and sufficiently terrifying but his son was there and that was what mattered. Grabbing him they managed to get him free of his chains but the red-faced-demon had seen them escaping and attacked.

He had grabbed his son and ran, escaping the Demons house he had ran down the stairs of the attic but now found himself in this strange void-like space, no way out and the spirits wandering around in the darkness thought they seemed to be noticing him and Dalton. In the distance he could hear the sound of begging and pleading and Dalton in his arms cried out. "Daddy listen, I think it's Mommy!

The spirits also seemed to be able to hear her voice as they began to look around scanning the void for the direction of Reiner's voice.

"Josh follow my voice!"

He turned around even as the voices of the spirits around him got louder and louder and they began to close in on him, he held the lantern aloft which seemed to keep them at bay somewhat but there were so many. He moved in the direction of her voice but was blocked by the dead, he tried to move around but there were too many, they were getting too close.

He held his son tighter to his body trying to protect him from the grabbing hands of the dead as he prepared himself for one last stand.

He sent a silent prayer to his wife and other children for forgiveness for abandoning them.

His thoughts and any further action were halted as out of the dark void exploded a pulse of brilliant white light the same colour of the lantern in his hand that's swept through the air in an ever-expanding pulse. The bright light illuminated everything around him and with it, he realised he was standing on the street outside his house. The spirits that had been surrounding him recoiled and scattered from the bright light and those who were hit screamed in pain, burn marks appearing on their pale skin. The strangest thing about the light though was the feeling it created inside him, warm positive emotions seemed to be coming from the light itself.

He blinked covering his eyes even as his son did the same thing in his arms trying desperately to see what the source of the bright light was even as it blinded them through its sheer intensity.

However, as soon as it had appeared it vanished leaving the world in darkness. He blinked trying to get the blindness out of his eyes even as Dalton asked. "Daddy what was that?"

"I don't know son, I don't know… but I think that someone is here to help us." He said trailing off hoping desperately that he was right whatever had driven off all those spirits was powerful beyond the Red-Faced-Demon, beyond the Black Bride and the Long-Haired Fiend. Whatever it was his instincts told him it could crush him like a bug and so he prayed that it was an ally, not a foe.

Out of the darkness though he saw a much smaller white light than before this one looked to be in the hand of a figure. Once more holding his son protectively he watched as the light got closer and closer until he saw the source of the light. A man, dressed in an open blue shirt and a brown coat over the top, he looked to be in his twenties with dark black hair and green eyes that even in the dull world of the Further glowed with otherworldly power. Authority seemed to radiate from every pore of his being and he didn't seem to be at all bothered being in this strange dimension, in fact he looked like he was going on a leisurely stroll.

"Are you two okay?" The man asked kindly, his eyes sparkling behind wire-thin spectacles.

Josh didn't know how to respond, the man's tone was at the level of casual conversation and it was both heartening and slightly disturbing. "Y-Yes I think so." He stuttered out before he seemed to focus on the man once more. "Who are you, you don't look like a spirit?" he asked suspicion in his voice, he wouldn't put it past one of the spirits to masquerade as normal to get the jump on them.

"Me, I'm just your average everyday Wizard I suppose." He said with a chuckle before replying with a serious tone to his voice. "My name is Harry Potter, don't worry I am like you alive. I came here to help."

Josh stared at him and nodded slowly, something about the man told him he was telling the truth. "My name is Josh Lambert, this is my son, Dalton."

The now named Harry nodded as Josh looked down at his boy he remembered what Elsie said about their bodies, they needed to get back to them before someone else did.

"Come on Josh follow the sound of my voice!"

All three of them heard the sound of her voice, it sounded panicked and scared. Josh threw all doubts about the man from his mind as he heard the sound of his wife's voice. "Come on then Mr Potter we have to go back to my house before one of the spirits gets our bodies!"

Announcing that he began to sprint for one of the houses, his house and as he made for the door he heard the sound of the other man running behind him but he ignored it as he grabbed for the door handle. Only to find it locked as he tried desperately to open it, the sound of his wife's panicked voice ringing in his ears.

Then he remembered the back door and he left the porch running around the house, hopping over the grass hedge as he went, the other man hot on his heels.

"We can get in through here!" he cried out as he grabbed the back door, this time it opened and he rushed through into the kitchen. The way illuminated by his lantern and the weird looking stick in the hand of Potter. All of a sudden though Josh felt sluggish as if something was weighing him down and as his son kept on trying to pull him forward he felt himself stopping.

"Come on Dad, we have to go!" Dalton shouted but josh could barely hear him, something was trying to keep him here. Harry meanwhile had moved around the man and seemed to be examining him, seeing more than either Josh or Dalton could but judging by the confused expression on his face he couldn't seem to identify what the problem was.

Josh wasn't focused on that, even with whatever was stopping him from going onward his main focus was his son. Turning to Harry Potter he came to a decision. "Go! Get my Son back to his body!"

The man looked as if he was going to argue for a moment before he nodded in understanding. "Come on then Dalton we have to go."

His son looked as if he was about to argue but looked at his father's stern face and he nodded turning around heading out the room, Harry hot on his heels.

Harry and Dalton burst out of the kitchen and made their way through the dim corridors of the house. Up the stairs, they made their way into a dimly lit corridor. "Which one is your room Dalton?" Harry asked the young boy gently, hoping not to scare him.

"Um, I'm not sure." It was so dark he could barely see as he opened the first door only to find it empty. He took comfort in the light of the man behind him, something about him felt like his dad. Comforting and warm.

Moving onto the next door he tried to open it when the horrific visage of the Red-Skinned-Demon appeared in the crack. Dalton backed up in terror when a white light exploded out of the stick which looked a lot like a wand in Harry's hand. It was shaped like a shield and blocked the Demon from exiting the room.

The Red-Faced-Demon seemed to shriek at the sight of the light and backed away further into the room. Dalton turned and looked at the man standing over him, his green eyes were actually glowing even in the misty world of the Further, the wand? Yes definitely wand in his hand was glowing at the tip as he flicked it turning the shield into a ball of pure light which he flung into the room though the door smashing the Demon in the face sending it flying into the darkness of the room with a shriek. Harry then grabbed the door and slammed it shut.

"Not that one then?" Harry asked Dalton, his voice dry and sarcastic.

"H-How did you do that?" Dalton asked trembling slightly as he tried to get a hold of his terror.

"Ah, I am a Wizard, I can use magic." he said smiling as he showed Dalton the Wand in his hand. "Now come on let's get you back to your body." As he motioned towards the last door in the hall.

Dalton nodded and turned to look at the man. "Will we see you again?"

Harry nodded and said. "Yeah, I'll stick around to see if you and your dad are alright."

Dalton let out a small smile, despite literally having just met the man he felt he could trust him. There was just something about him that made him feel comfortable and safe.

Together the two made their way into the last room Harry raising his wand one last time, sending a blast of white light towards the cupboard silencing any of the sprits that were in there.

"Well go on then Dalton time to go back to your body." Harry said with a smile.

"Thank you, Mr Potter." He said with a smiled as he turned towards his body even as Harry scanned the room for any spirits that wanted the child's body. The only direction they seemed to have come from was the clothes cupboard.

As the boy's spirit and body became one once more he grabbed hold of the Resurrection Stone once more and let reality fade back into existence even as he cast a Notice-Me-Not and a Disillusionment Charm over his body as he backed into one of the corners watching as Dalton awoke. A woman watching over him even as a man with a flashlight still watched the cupboard warily.

He watched as the women picked up the waking boy and taking him out of the room, the man looking wildly around the room before following after them. Harry detached himself from his place by the wall and followed after them as they made their way down the stairs to the rest of the family.

There was an older blond woman, another light totting young man in the room along with another women sitting in front of a chair

"He's awake." Said the women holding Dalton as she presented him to the other women who smiled.

"My boy!" her voice was filled with such joy that it brought a smile to his face.

The blond-haired women looked utterly relieved as she squeezed the shoulder of one of the light welding men, the one who had been in Dalton's room earlier smiling in relief. Harry was doing the same, it seemed like the family had been terrorized by spirits for quite some time and were just relieved that it was over.

Harry was still smiling about to leave when something about Josh caught his eye. He looked closer before his eyes widened in shock and anger. Cancelling the spells on his body he took a step forward from out of the shadows.

"Get Dalton off of him." Harry said as he announced himself to the room. The two white-dressed men whirled around in shock aiming their lights at him as if he was one of the ghosts. The older blond women looked shocked as she stared at the wand in his hand as if she reorganised it for what it was. Both of the brown-haired women looked shocked and terrified at his appearance.

Though the lethargic Dalton gave him a weak if confused smile wondering what he was talking about as he sat curled up in his father's lap. Though it was Josh's reaction that was the most telling, he looked a mixture of confused and terrified.

"Elise, the light isn't driving him off!" One of the two men shouted in fear glancing at the older blond in worry.

"It won't because he's not dead." She replied shortly as she continued to stare at Harry warily.

"Who is he then?" Asked one of the men.

"He is a Wizard." The women said shortly as she stared at Harry with a wary look in her eyes. "What is it you want here?"

Harry stared at the muggles who were all looking fearfully at him though it was probably understanding. Deciding to go for a gentler approach he raised his hands and said gently. "My name is Harry Potter, I am not your enemy. Ask Dalton he saw me in The Further."

Everyone continued to look warily at him though the now identified Elise glanced at the now awake Dalton who nodded and said weakly. "H-He helped us in there, got rid of the bad Demon when it attacked me."

Elsie though seemed to freeze as if some knowledge had just percolated into her brain. "H-Harry Potter, did you say?"

Ah, it seemed as if someone here knew who he was. "Yes Ma'am that is me. I take it you know who I am?"

"Yes, I do." Turning to the others in the room she said. "He isn't one of the ghosts nor is he an enemy, not that we could fight him if he wanted us dead." She finished with a sigh as she turned back to look at Harry. "How can we help you, Mr Potter?"

Harry just nodded as he took control of the situation once more. "Mr Lambert could you please grab your son and step away from your husband." He said hoping the women would listen to him.

"W-What, why?" she asked in confusion.

"Because that isn't your husband." He said as he lashed out with his wand, he didn't want to give whatever spirit had invaded to hurt Dalton who had been very brave in the Further and didn't deserve to be harmed by a being masquerading in his father's body. Two spells cast consecutively blew the two women by Josh away floating up into the air and out of harm's way whilst one more summoned Dalton out of his father's arms and towards Harry. The last spell was an Incarcerous Spell that shot out of his wand and hit the possessed man straight in the stomach, its bindings wrapping around him keeping him tied to the seat.

"What are you doing?" Screeched Renai as she looked fearfully between her tied up husband and her confused son who had been put down in one of the other chairs.

"That is not Josh." He said as he kept his wand steady.

"What?" Elsie asked bewildered before a thought struck her and she paled. Reaching over she grabbed hold of a camera from one of the bags and put it to her face, the flash of the camera lit up the room as everyone turned to her to see what she was doing. Though the most surprising reaction was from Josh himself he looked as if he was about to go into a rage.

"What! Why would you do that! You know I hate having my picture taken!" he shouted, spit coming out of his mouth as he tried to get up. "Why!" he roared. Before he could continue his triad Harry waved his wand once more and Josh seized to make any more sound even as his mouth continued to move.

Elise took a look at the picture and grimaced as she looked at the image on the screen. "He's right. He's right. That isn't Josh."

That seemed enough to get Renai's attention as she looked bewilderedly towards Elise, Dalton and everyone else doing the same thing. Elise took a deep breath and turned the camera around showing everyone in the room the picture. Sitting in the chair tied up wasn't josh in the picture instead it was a screaming woman with chalk-white makeup covering her face wearing a pitch-black dress.

"What, what's wrong with my husband!" Shouted Renai now utterly horrified.

"He is being possessed, possessed by the same spirit that haunted him when he was a child." Elise said grimly before turning to Harry. "Can you exorcise it?"

Harry nodded before looking at the struggling Josh. "Yeah I can, how do you know about Wizards?"

Elise shrugged and said. "Found out I was a Squib. Met a Wizard who was nice enough to tell me what that meant."

Harry nodded as he pulled the Resurrection Stone off his neck and held it in his hand as he approached the still raging Josh. Josh tried to snap at him with his mouth, saliva dribbling from between his teeth.

Putting the Stone to his forehead, Josh went rigid as the Stone caught hold of the spirit within. Through the connection with the Stone, he learnt the name of the Spirit, Parker Crane but he did not focus trying to read the spirit's soul to get its story.

Pulling the Stone away from Josh's head the screaming form of a black-dressed figure which was devoured by the Stone. Harry smiled as the spirit disappeared into the Stone where it would be trapped for eternity. Josh's body crumpled no longer responsive without a spirit to inhabit it, ignoring everyone else he spun the Stone three times in his palm. The astral copy of Josh appearing in front of him.

"W-What?" The ghost seemed incredibly confused but Harry just smiled and said.

"There is your body Mr Lambert."

Josh seemed to register that as he looked around the room and saw everyone staring at him and his body. With a smile, he entered his body once more and his form straightened up looking around with blurry eyes as he adapted once more to a body.

Smiling Harry backed off as Dalton ran towards his father grabbing him in a hug, Renai not far behind. Turning to Elise he motioned towards the front door, the women nodding as she followed him out though the two muggles who looked like they were with her made to follow only to be rebuffed by Elise as the two made their way out onto the front porch.

"It is a pleasure to meet you Mr Potter and thank you for your assistance in this case." Elise said into the silence.

Harry though just waved it off. "It is fine, it was easy for me after all."

"Well thank you anyway." Elise said before glancing back at the house. "Will he be alright?"

"Yes Mr Josh Lambert will be fine, the Spirit is in here and won't be hurting anyone ever again." He said as he patted the Stone. "Now I had best be off, hopefully, we shall not meet again, goodbye."

With that, he vanished from her sight as he disappeared back into the Further. He was about to vanish back to his domain when something about the house appeared wrong. The house door was closed now but with a simple unlocking charm it blew open and he entered the house, he was drawn upwards towards the top of the stairs and into one of the bedrooms. A lanky haired figure stood leaning over the crib of a baby reaching for the child.

"Oh no you don't!" Harry cried blasting the figure out of the window with a burst of white light.

Lowering his wand he created a hole in the dimensions before vanishing. He reappeared back in the library of the Black family home cloaking himself from the Further once more as he sat and picked up his book. The silence of the house putting his mind at ease once more.