Nineteen Years Later...
Harry dropped the battered old trunk and new Broomstick he'd been carrying to the floor and closed the classroom door behind him with a satisfying click. He heaved a shaky sigh and peered around at the familiar space, as he moved between desks to rearrange them, memories flashed before his eyes, as vivid as if he'd just dove head first into a pensieve; a purple turban, a swarm of pixies, a grindylow tank, an electric blue eye, a simpering giggle and a black bat-like cloak. For better or worse, Harry realised he had certainly learned a lot in this room, even if it was more often than not, what not to do.
He felt wonderful today, if more than a little emotional. The thought of being so far away from Ginny for so long was particularly painful but she'd promised to come and visit Hogwarts to help Madame Hooch with flying lessons and refereeing duties, providing she could get the time off, being the star player for the Wimbourne Wasps Quidditch team had it's perks after all.
Harry moved to the front of the classroom brushing the tips of his fingers along the stone walls absent-mindedly, he saw a letter addressed to him laying on his desk. He recognised the untidy scrawl immediately and tore open Ron's letter.
"Oh Harry! I wondered when you'd be arriving! How are you?" Harry hastily stashed the letter into a pocket of his robes and grinned up at Hogwarts' Deputy Headmistress. "A little overwhelmed to be honest Hermione". She crossed the room and his face was enveloped by her mass of bushy hair as she hugged him. "I know you'll be wonderful Harry! Plus at least your lessons for the fifth years will be a breeze, I found the notes I took of all the DA lessons you gave us and rewrote them so you didn't have to worry about a lesson plan for them because, well... you already did it years ago" Of course she'd written notes Harry mused. "my handwriting was atrocious back then, you'd never have understood what it all said" Harry snorted at this, after so many evenings copying her notes in the Gryffindor common room, he knew perfectly well that her handwriting at fifteen years old had been better than most of their teachers, and he had a feeling that she'd rewritten them more out of fun than anything. Even so, Harry was interested in looking through them "You have worked out a syllabus for the students haven't you Harry?" her face apprehensive. "Ah umm…" grimaced Harry, as his friend's eyes grew wide with horror. "I'm kidding Hermione, of course I have".
Truthfully, Harry had been imagining what his lessons would be like for years and already had several sheaves of parchment with ideas scribbled on, ranging between techniques for using particularly useful jinxes, and objects imbued with powerful protective enchantments, to a whole terms worth of lessons dedicated to investigating and standing up to witches and wizards in positions of power, with a hundred house points awarded to the first student that mentions The Daily Prophet.
"Although would you mind looking it over and telling me what I should change? I'm not sure if I should teach them the Patronus charm in their third year, I mean I learned it then but it was really difficult and it took me ages to properly get to grips-"
"I'm sorry, I can't right now." Said Hermione as she swept her wand through the air causing the thin layer of dust that had built up over the summer to rise up and drift out through an open window. "Professor McGonagall said she'll be dropping by at some point after she's finished renegotiating salaries for the kitchen staff, perhaps she could help" Hermione couldn't stop herself from beaming at the thought of the Hogwarts kitchens.
The campaign to get S.P.E.W. officially recognized by the Ministry of Magic as a legitimate cause had been a failure but with the help of Kreacher, Hermione had been able to help voice the concerns of House Elves, who had then gone on strike, demanding wages and time off for holidays and birthdays, the House Elves then began asking anyone they spoke to when their birthday was, and taking the rest of the day off if the answer was "today". Hogwarts began hiring witches, wizards, goblins house elves and one infamous Leprechaun who according to Neville, was responsible for the best Goulash ever made, to work full time in the kitchens from then on.
I might be able to look at it this evening but I can't really stop just now, I have a hundred and one things I need to do before the students arrive tomorrow; I need to convince Peeves to tell me where he hid the Sapphires from the Ravenclaw house points hourglass, he's replaced them with dungbombs and we really need to make sure the Entrance Hall is properly aired out by tomorrow, plus I need to do the final preparations to the adult evening classes, I know Hagrid said he wants to start at the intermediary level but I think it's for the best if he just starts from scratch don't you?" she tapped her wand thoughtfully against her cheek, causing purple sparks to come dangerously close to setting her frizzy hair alight.
"Yeah, I think that's probably wise" Harry chuckled, pulling his mind away from the memory of a curly pig's tail sprouting from his cousin's backside.
"Oh that reminds me, do you know if Arthur will definitely be coming to my Muggle Studies lesson? I meant to send him an owl but I completely forgot"
"He's really looking forward to it, although i'm not sure if he's more excited to be learning about microwaves or to be bragging to everyone else in the class that he's the father-in-law of their professor"
Hermione looked exasperated but blushed slightly all the same "I've told him so many times that I can't be seen giving him preferential treatment..." "Well you're the one that has to face Molly at Christmas if he ends up with a Troll grade" Harry shrugged.
"Don't be silly, I'm sure he'll be my star pupil" Hermione said with determination, although she didn't look quite as convinced as she sounded. "Anyway Harry, I should get going. Don't forget to bring your lesson plans with you this evening, it was lovely to see you!" She waved brightly and hurried out of the classroom. "Yeah, you t- hang on we saw each other at The Burrow two days ago!" He called after her.
Harry lifted the notes she had brought him from his desk and as he did so, his hand passed through an arc of golden summer sunshine melting into the Defence Against the Dark Arts classroom and briefly illuminated a scar so faded it was barely visible "I MUST NOT TELL LIES". Spurred on by a fierce defiance that had never fully left him, he drew his holly and phoenix feather wand and sent the desks crashing towards the walls, clearing a space in the middle of the room and making a mental note to ask Hagrid if he'd be able to find him a boggart.
He had learned by doing, he thought. And wrote the word "EXPELLIARMUS" in large curvy letters on the blackboard behind the teacher's desk. His desk. This was the spell that had saved his life on more than one occasion, so this. Harry thought, was the most important spell to start with. Once a long time ago Lupin had implored him not to let it become his signature move, and although spells like Stupefy and Petrificus Totallus came in handy, it was Expelliarmus that Harry found the most comfortable. Opponents were still conscious so they could be reasoned with and wouldn't be provoked into furious recklessness once they regained mobility.
Harry paced the room reading Hermione's notes, wondering if he'd be able to find some useful items in Weasley's Wizard Wheezes he could use in some of his classes. He noticed something out of the corner of his eye and froze, he was positive there hadn't always been a door off to the side, he'd have noticed it during the hours and hours he'd spent in here as a young wizard, yet there it was, a cupboard under the stairway that lead up to his office. Slowly Harry rolled up the pages of parchment he was reading and slid them into the moleskin pouch he wore around his neck. He unlocked the highly polished brass latch and pulled the door open.
Inside was a space he'd become well accustomed to, a spacious room lit with flickering torches. Wooden shelves lined the right hand wall filled with secrecy sensors, sneakoscopes and numerous other magical instruments he had a vague recollection of smashing in a fit of rage a long time ago. Along the left hand wall were wooden bookcases filled with almost as many books as he was sure Hermione had ever read. The floor was dotted with dozens of large squashy cushions. The Room of Requirement had served him well in the past, and now it had revealed itself to help him again, another old friend extending it's hand. Where previously stood the cracked Foe Glass Dumbledore's Army had used to keep track of how close Umbridge and her Inquisitorial Squad got to their secret hideout, instead stood a large stone mirror, across the top was engraved "ERISED STRA EHRU OYT UBE CAFRU OYT ON WOHSI"
He took a step towards the Mirror of Erised, then another. He found he couldn't bring himself to look into it, choosing instead to gaze at the floor. Harry realized he didn't have the desperation to stare into it that he once did. Part of him understood that this would be the final time he would see the mirror. Looking up he saw himself, sat at a table in a familiar pub. His arm around his fiance, laughing with Ron, Hermione looking up from amending the same sheaves of parchment that were currently in his trunk. Hagrid, Neville, Luna and all the Weasley's were there. Once he had looked into the Mirror of Erised and seen himself surrounded by family he had never known and would never know, an impossible sight that he became obsessed with experiencing. Now, he saw a vision that was simply hours away from becoming reality. The family that had found him and fought with him. The family that he had willingly sacrificed his own life for, and together had finally defeated the greatest evil the wizarding world had ever known.
The joy he saw on the faces of everyone in the mirror he found inspired him to leave preparing for his lessons until tomorrow. For now, he thought, he decided to go and find Hagrid and Neville in the castle grounds, and walk with them into Hogsmead. He turned and left the Room of Requirement, mind buzzing with new possibilities on how to spend the next several years. Harry felt an immeasurable amount of comfort being back at Hogwarts. As he strolled down into the grounds, he raised his hand absent-mindedly and touched the lightning scar on his forehead.
"It's good to be home." he muttered
The scar had not pained Harry for nineteen years. All was well.