Hey all, I've come out of the depths to share this little piece with you. I do not own anything.

Summary: When Harry steps into Grimmauld Place over the at the beginning of his fifth year, the ancestral home awakens something in him that will not allow him to leave things as they are, and changes several events irrecoverably. Maybe even the power He knows not. OCD!Harry

Initially, when Harry Potter stepped into the Ancestral Home of the Blacks, he thought little of the dark shadows, cobwebs, and all around unsanitary dirtiness of the house. It did not bother him when dear old Walburga Black opened up her gaping maw and screeched about the disgusting half-blood that dare tread where the superior feet of purebloods had once tread.

It was none of those rather unsavory things that made Harry Potter pull up short and simply stare towards the dirty object of his ire. The expression on Harry's face was not one that any who knew him would be surprised to see on his face. It happened when Harry was forced to eat asparagus, when Ron chewed too loudly in his ear, and when Hermione took his things without asking.

It was the "You Dare to Exist in My Space" look.

It was a look commonly put into use by Petunia Dursley, if anyone was interested in that fact. Not that anyone in the house knew the origins of that look. His friends simply knew that if Harry turned that look to you, you would receive a scolding on par with Hermione's homework spiels.

There were many things that Harry was attuned to in his many years under the loving care of his relatives. The first of these things was an impulsive need to get rid of clutter.

The terrifying days when Ron left out his snack wrappers, left his clothes over his trunk haphazardly or Merlin forbid it- his Chocolate Frog collection laying about, he was sure to either have all of his snacks mysteriously vanish, his clothes smelling of Lavender, or his Chocolate Frogs held hostage. Harry was a relentless and ruthless foe when it came to leaving things where they obviously did not belong. Dust bunnies huddled together in corners, clothes began to fold themselves, and Ron learned that his collection should stay firmly out of Harry's sight.

The twins once made the mistake of leaving their dorm room door open, and Harry wandered in with a Charms question on the tip of his tongue. Fred and George were the only ones witness to what happened that day, and every day since then they presented themselves and their room to Harry at least once a week for inspection. Harry was pleased with their progress, perhaps he would even start allowing them to use their abandoned classroom for experiments next year.

Not all of Gryffindor house fell under Harry's scrutinizing eyes, but all knew that anyone the twins held in such respect also demanded their complete subservience in all areas.

House elves did not even need to clean the Gryffindor common room anymore.

When the twins, Ron, and Hermione were told that Harry was coming to the dilapidated house there was suddenly a heavy tension in the air.

"We need to warn him." Hermione hissed through her teeth at Ron, who nodded and absently rearranged his Chocolate Frogs into a neat pyramid. She was situated on the now clean rug of Ron's room, which had been scrubbed with frantic hands for hours over the past two days. It was another three days until the plan to retrieve Harry would be put into place. The house still would not be left standing in Harry's wake.

"'Mione, you know that they'll never believe that Harry is going to rip the house apart. Besides, Dumbledore said-"

"I don't care what Dumbledore says!" Hermione shrieked, finally over her limit of acceptance of authority. After all, she was staring in the face of an oncoming storm. Harry would never forgive her for allowing the house to be in this state when he arrived.

"Remember when he caught the fungus that Neville was growing under his bed?! He didn't speak to poor Neville until his fungus was removed from the room and Neville brought him a basket of treacle tart!" Ron paled- there was a lot more than fungus growing in the corners of this house.

"Bloody hell we need to tell him." Hermione got up and began pacing, not even scolding Ron on his language. Time was of the essence in this situation.

She paced for several minutes, and Ron straightened his unopened school books on his temporary desk. Hermione stopped for a moment, eyes widening as she looked at Ron's pile of dirty clothing in the corner.

"We can't send a letter, Dumbledore would know. But we know someone with a way around Dumbledore…" Hermione chewed on her lip, something Harry couldn't scold her for yet.

"We do?" Ron stacked his quills in his quill box by color.

"Dobby!" Hermione cried in triumph, eyes gleaming.

A pop followed her call, and a small, spindly house elf with socks hanging off his ears stood in the room, beaming up at Hermione.

"Miss Grangy be calling for Dobby?"

Hermione nodded, smiling down at the little creature.

"Could we ask you a favor, Dobby?" The house elf looked around the dimly lit room briefly, then nodded enthusiastically.

"Anything for friends of Great Wizard Harry Potter!"

"It actually has to do with Harry, Dobby. We need you to bring him a message tonight. He needs to know what he's coming into…"

That evening, around 11 o'clock, a figure appeared in the middle of the second bedroom of Dudley Dursley. It was small, with abnormally long fingers and bulbous eyes. The room the creature had appeared in was bathed in moonlight, revealing the spotless wooden floors, the perfectly organized recipe books on the gleaming desk, and the neatly folded clothes made for a baby elephant stacked upright on a lopsided chair.

A body that was certainly not a baby elephant was lying on the sagging mattress pushed to the side of the room. It sat up and looked at Dobby, who walked over to the bed and looked up into the eyes of his beloved Harry Potter.

"Mister Harry Potter is being asked to get a message from his Wheezy and his Grangy." He beamed up at the black-haired wizard.

That got Harry's attention. He had been stewing on the fact that none of his friends had been in contact with him this summer. He had been going on more cleaning spells than usual to distract himself from this fact.

He smiled at his friend, his connection to his other friends.

"What is the message, Dobby?"

"Harry Potter sir will be going to his dogfather's house! Wheezy and Grangy will be there too! Miss Grangy says to warn Harry Potter that the house is not "to Harry Potter's Standards of Living"." Harry did not know where Dobby had picked up making quotation marks but he appreciated it nonetheless. He leaned back against the wall behind his bed and was silent for several seconds.

"Thank you, Dobby. I might ask for your help when I go in a couple days. I will not let things stay in the state they're in, if 'Mione was worried enough to send you. By the way, why haven't they sent anything with you before?"

Dobby rocked back on his heels for a second, before relenting and speaking. Miss Grangy hadn't said he couldn't tell Master Harry Potter…

"Mister Dumbles said that you had to be lonesome this summer, and that Master Potter's owl wasn't safe."

Harry's eyes narrowed minutely, before he shook his head and stood. He patted Dobby on the head and thanked him for the message, giving his regards to Hermione and Ron before sending him off, the elf beaming like it was Christmas the entire time.

Harry had some plotting to get done. Dumbledore obviously did not have his best interests at heart if Hermione could think of a safer way than to get into contact with the recently traumatized teen than he could. Or he had thought of it and decided that Harry should be alone with his nightmares all summer. He was coming for Dumbledore's office next.

Days later, Harry stood in the entryway to what must have been the biggest nightmare his aunt could cook up for him. The walls were streaked with grime, gruesome wallpaper depicted decapitation and the ugliest umbrella stand he had ever seen took up a corner, draped elegantly with spiderwebs and some sort of moss growing on its…toenail?

"What is this place?" Nobody took note of the dangerous tone creeping into his voice. They assumed he was simply mildly concerned by the grime of the house, rather than two steps from an explosion, as he truly was. From upstairs, Harry could hear several low "meep"s and he instantly went up to the second landing, which if possible, was worse than the foyer.

"Harry!", came several yells, although none of the five teenagers emerged out of their recently cleaned hiding place to hug him. He didn't mind, he did not want to touch anything in this house either, person or otherwise.

"Your warning wasn't enough." Harry said, eyes gleaming as they took in the decapitated elf heads adorning the wall symmetrically. At least they were symmetrical, but that wasn't going to stop him from throwing them in the rubbish bins and burning the bins for good measure. They matched the wallpaper downstairs as well, at least the person living here knew how to coordinate. Speaking of which…

"Where are we?"

"Oh! No one told you! This is the headquarters of the Order of the Pheonix, Harry. It's an organization founded by Dumbledore to combat You-Know-Who in the First War." Hermione had stood from the littler alcove that she was smooshed into with four redheads. Hesitantly, she walked closer to Harry and gave him a look-over.

He had grown to a respectable height this summer, although how that was possible with the Dursleys as caretakers was a mystery to her. His hair had gotten even longer, although the shagginess had been offset by the length and curled lightly near his collarbones. She rather liked it now, and told him so.

"Thank you, Hermione, I haven't really had the mind to cut it." Her heart sank when Harry said that. They had only contacted him when they needed to warn him of what he was walking into. But other than that, they had left him to his own despair of the events preceding the summer. She stepped forward and wrapped her arms around her closest friend, murmuring apologies incessantly. The Weasley children also emerged from the alcove to see Harry gently push Hermione away from him and smile.

"Don't worry, you contacted me eventually. And Dobby told me why, so I know who did it. The headmaster is not going to enjoy his visits to this house."

The twins exchanged a look. Dumbledore had awoken a dangerous sleeping dragon with his actions this summer, and they would bear witness to the famous Potter temper in a purely Slytherin execution.

Harry's on the warpath. Fred thought as he saw the smile Harry was giving Hermione turn to a sharp smile edged with dark promises.

Past

The last time Harry had been angered enough to turn to a cold revenge, he had taken it out on Seamus Finnegan. Seamus had had the nerve to go through Harry's things and leave them in disarray following his ill-rationalized venture.

Harry had walked in while he was doing this and had not interrupted Seamus' nosy wanderings. Instead, he had waited until Seamus had clumsily put everything back before clearing his throat.

"Harry!" Seamus yelped, as he realized the object of his scrutiny was in the room while he rifled through his things. Harry just narrowed his bright green eyes and left the room without answering. It was not until Seamus fell into the same trick stair three times, had couches move out from underneath him, and doors slam themselves into his face that he realized the entire castle was out to get him. It took another two weeks for him to become utterly miserable and figure out that it was Harry who had instigated the whole thing.

Seamus finally gathered the courage to talk to Harry during dinner, sliding a plate of treacle tart across the table from the seat he had grabbed early just for this reason. Harry locked eyes with Seamus, even as he pulled the plate towards him.

"I won't do it again Harry, I promise. I don't know what I was thinking, I was panicking about the essay due." He had in fact been looking for Harry's essay, and not finding it was simply rifling through his extremely private dormmate's things.

Harry looked at him for several heartbeats, before nodding.

"I'll tell the castle to stop." He did not elaborate, but suddenly Seamus noticed that the walls had seemed much closer seconds ago, and his bench was suddenly much more comfortable than before. Even the plates seemed to gleam more brightly. Seamus gulped as he realized that Harry had the entire castle keeping tabs on him from that time. Bloody terrifying, he thought as Harry happily stroked the shiny bench beside him and bite into the tart.

Present

Everyone in Gryffindor gained a respect for the quiet Boy-Who-Lived that day. If suddenly the pillows were always fluffed and the beds always made before the house elves could get to them, it was never mentioned.

It was terrifying the control Harry Potter had over the everyday activities of the castle. No one outside the tower realized it was Harry to constantly trip Draco Malfoy over rugs, make Snape's door suddenly harder for him to bang open, and surreptitiously slide Ginny Weasley and Colin Creevey further down the Gryffindor table from him.

Harry Potter could be extremely subtle in his revenge, and his house knew that sometimes accidents around Harry weren't accidents at all.

Soon the rest of the Order of the Phoenix would realize this too, after all that Dumbledore had put him through this summer. Of course, in Harry's mind, it also fell on the members of the order who had mindlessly followed their esteemed leader and left a traumatized teen locked in his room.

Harry reached out to the sentient magic of Grimmauld Place, letting his magic intertwine with the house and felt what seemed like a sigh of contentment, of home sank through to his core. The house felt as though it had been abandoned and left to its own devices for years. The magic of the house hadn't gone into hibernation, but had been growing and infusing with more and more objects within the house in that time. That meant that Harry now had control over the entire house. From the bannisters and staircases to the stoves and cobwebs on the ceiling- the entire house was his to command.

Harry smirked.