If Time-Travel is possible, where are the tourists from the future?

-Stephen Hawking

Harry ducked as a stream of light flew over his head. He shielded, then shot an expelliarmus back at the Death Eater. "Dean!" he shouted. "Take Seamus, Terry and Susan and go round the back. Use disillusionment charms!" Harry's former roommate Dean Thomas nodded quickly in assent, and the three aforementioned tapped themselves with their wands and promptly disappeared, leaving nothing but a slight shimmer behind. Ron and Harry shared a look, and advanced towards the house, working together and Ron held up a protego, while Harry shot offensive spells at the enemies.

Even now, three years after the defeat of the Dark Lord Voldemort on the 2nd of May, they were still rounding up his followers. Harry Potter had joined the aurors straight after the Battle of Hogwarts, never even completing his seventh year of school. Now, at 21 years of age, he was still fighting Death Eaters. But this time he was not alone. Many members of the DA had become aurors, and today he was joined on this raid by Dean Thomas, Seamus Finnegan, Terry Boot, Susan Bones, and of course, his lifelong friend Ronald Weasley. They had recently located a safe house being used by former followers of Voldemort, and were now attacking it.

As the Boy-Who-Lived and his best friend advanced, they saw the faces of the Death Eaters. Alecto and Amycus Carrow, who had escaped Ravenclaw Tower during the Battle of Hogwarts. Harland Selwyn, responsible for bullying Xenophilius Lovegood after Luna's capture. Merton Travers, who had aided him and murdered of Marlene Mckinnon, member of the Order of the Phoenix during the first war with Voldemort.

Harry dueled Selwyn, quickly stupefied him, and tied him up with incarcerous. Meanwhile Ron fought Travers, and Seamus, Terry and Susan appeared from behind the Death Eaters, quickly joining the battle. Terry punched Amycus Carrow in the face. "That was for beating me up in seventh year."

Needless to say, the Death Eaters were apprehended and subsequently imprisoned.

Harry Potter sat in his office, doing paper work. He sighed. This was undoubtedly the worst part of being an auror. His thoughts drifted back to the aftermath of the war while filing a report. After Voldemort's defeat, he had fulfilled his dream of joining the aurors, and gone through training. And the people, that had been a nightmare. Everyone had been so adoring, so happy, so grateful. They gave him awards, even an Order of Merlin, First class. But it meant nothing. (Though he didn't mind them giving him a chocolate frog card.) The country rejoiced, while the heroes mourned. Mourned for their dead friends, family and loved ones.

And Harry mourned too. He mourned, not just for the dead, but for himself. For the childhood he had never had, and the teenage dreams that had been ripped away from him. He had never gotten back together with Ginny. It just hadn't felt right anymore. But he had continued on with his life. He threw himself into his work, he continued learning, and he forgave Dumbledore.

He remembered the old Headmaster once saying, "Do not pity the dead, Harry. Pity the living and above all, those who live without love."

His thoughts were brought back to the present as a drop of ink dripped from his quill. He also remembered Dumbledore saying that it did not do to dwell of dreams, and forget to live. He packed up his things, and apparated away to the front gates of Hogwarts, as close as you could get before the wards stopped you. Minerva had asked him to come visit at the request of Dumbledore's portrait.

He entered the grounds, making his way to the Headmaster's office. Headmistress' now, he thought. He used a secret passage to get there faster, ducking behind a tapestry and whispering the password (silendum). He came before the gargoyle, and said "Shock-O-Choc". Minerva had continued using various candies as passwords for her office, to honour the late Headmaster. It opened, and he walked up the stairs.

"You've got to be kidding me."

Those were the first words out of his mouth when they explained to him what they wanted him to do.

"You're absolutely mad. Barking!" Minerva gave him a stern look. "I can assure you Mr Potter, my mental health is not in danger. It's quite simple really, you need a vacation, and are proficient in Defence against the Dark Arts. You have taught it before. What's more, they could use at least one decent teacher, especially in those times. Your belongings have been gathered by the House Elves."

There was no protesting, he was fighting a losing battle. "Alright I'll do it."

"Good. Albus left me precise instructions for this spell. He created it. Viginti Trium Annorum Redire"

Harry James Potter, Boy-Who-Lived, Man-Who-Conquered, and whatever other stupid titles he had been given, appeared in front of Hogwarts, bag in hand, on Monday the 29th of August, 1977.

He went to the Headmaster's office, retracing his footsteps from earlier. Or later, he mused. Time travel.

He arrived at the gargoyle, and realised that he did not know the password. "Okay, er, Fizzing Whizzbees? Jelly Slugs? Pepper Imps? Sugar Quills? Chocolate Frogs? Ice Mice? Fudg- Oh, chocolate frogs." He climbed the stairs past the gargoyle.

Albus Percival Wulfric Brian Dumbledore was sitting in his office. He had had quite a normal day, and he was hoping that it would become a lot more interesting. So far, the most unusual thing that had happened was when he had accidentally taken a matching pair of socks from his sock drawer. Of course he had put one back and taken another, because really, wearing socks that matched? He had a reputation to uphold! Then he heard the soft chime of the alert that meant that someone was coming up the stairs to his office. He frowned, school hadn't started yet, so the castle was empty. Who could it be?

The door opened, and in walked a young man, in his early twenties. He was tall, and muscled, with striking green eyes and shoulder-length messy black hair, a streak of white in it. From stress, perhaps? The stranger was wearing scarlet auror robes, and carried a bag in his hand. He had a scar in the shape of a stylized lightning bolt on his forehead. His face seemed familiar, but the old Headmaster couldn't quite place it.

"Headmaster. I've come to apply for a job. I hear the Defence against the Dark Arts post is open?"

Harry walked into the office and saw the silver instruments clicking and whirring, the same old desk with its usual bowl of lemon drops, and Albus Dumbledore, alive and twenty-three years younger than when he had last seen him. (Not counting his portrait.)

"Headmaster. I've come to apply for a job. I hear the Defence against the Dark Arts post is empty?"

Dumbledore seemed taken aback. "Yes it is. And who might you be?" he enquired. Harry gave a wry smile. "That's actually quite a long story. So, to put it plainly, I'm from twenty-three years in the future, and your portrait and Professor McGonagall sent me back in time with a spell you invented. My name is Harry Potter, son of James Potter and Lily Potter, née Evans. I believe they are seventh year students right now?"

Dumbledore gaped for a moment, then collected himself. "Do you have any proof?" Harry nodded and handed him a letter, written by Professor McGonagall.

Dear Albus of year 1977,

This is Harry James Potter, born in 1980. He is who he says he is, and has full qualifications in Defence against the Dark Arts, he is an auror and has taught defence before. His false name will be Harry Privet. He will return to 2001 at the end of the year, you need merely say tu dimissi viatorem and he will be transported home.

Minerva McGonagall

Headmistress of Hogwarts School of Witchcraft and Wizardry

P.S. Your favourite flavour of jam is raspberry.

After reading the letter, Dumbledore looked up and smiled sadly. "In your time I'm dead, aren't I?" Harry nodded slowly. "You are. I can't tell you more about the future." Dumbledore inclined his head. "Of course. I believe you. It says here you have taught defence before?" Harry smiled in remembrance. "Yes, in my fifth year, the defence teacher was horrible, so we made a club called Dumbledore's Army, or the DA for short, which I taught."

Albus smiled. "Well, you're hired. Here's your schedule, school starts on Friday for everyone except the first years, as we like to give them time to settle in; they'll have a long weekend. I trust you know where the defence teacher's rooms are?" When Harry affirmed the statement, his eyes twinkled and he said "Good day. I look forward to working with you." Harry replied "Good day Headmaster Dumbledore."

"Please Harry, call me Albus. We are colleagues." Harry smiled and waved "Good bye Albus."

As he made his way to his rooms, he whistled a cheerful tune that he had heard Dumbledore himself whistling in the past, though he didn't have a clue as to what the words were. He arrived in front of a portrait, who had obviously been told of his arrival by a House Elf. The portrait introduced himself as Russell, and Harry set his password to 'Hope is the only thing stronger than fear.' He went inside, dropped his bag on the ground and went to bed exhausted by the day he'd had.

He'd need his sleep for what was yet to come.