In his second year, Harry poisoned Lockhart with a very potent truth serum that he had mixed with a babbling potion – causing the man to lose all his credibility. He also met and killed a basilisk, saved Ginny's life, almost lost Banders – to the basilisk – and was able to send another part of Riddle's soul to meet Death. He then spent his summer renovating the house in Grimmauld Place and making friends with Kreacher and Mrs Black. He also destroyed Slytherin's locket that summer when he felt a piece of Voldemort's soul attached to it. Kreacher was most pleased that his final order from Regulus Black had finally been fulfilled.
In his third year, the trial of Sirius Black finally came to an end – when Harry sent Scabbers as the final piece of evidence for the defence. Ron was very mad, accused Bandersnatch and Hermione's cat Crookshanks in equal amounts of having eaten the rat, but Harry had reminded Ron of the small deal from the day they met in the train in first year. He bought Ron a small owl anyway, just to shut the annoying red-head up. He also got to meet Remus Lupin at last, and offered the tired looking man his parent's house out in the Lake district if teaching didn't work out for him – which it didn't, but Remus moved in with Sirius in Grimmauld Place, since it was no longer so drear.
Third year he had also taken, and then quickly dropped Divinations, when the professor had screamed at seeing the Grim in his teacup and portents of death all around him. She'd screamed even louder when he'd brought Bandersnatch to class and explained to her that sometimes a dog was just a dog, even if it was big and black. He'd taken up Ancient Runes instead.
In fourth year, shortly after names had been read out of the Goblet, Harry stole the hipflask of the defence teacher just before the hour was up, and everyone in the Great Hall saw what an imposter he was. He was rather pleased with that bit of revenge. Until Fudge came to deal with it, and Hogwarts had its first experience with Dementors – or as he had already come to know them from his time Away: Auditors. These ones were slightly different though. Of course, they were still deeply unpleasant. Then there was the whole Triwizard Tournament thing to deal with of course – Ron didn't talk to him for the entire duration of it, but Harry decided it probably wasn't much of a loss. In the first task, Harry had locked eyes with his dragon and said, very clearly, "Sit," before taking the golden egg from the nest while the ferocious Hungarian Horntail just sat there. In the second, he'd dived into the lake and swum down, unconcerned. He'd accompanied Death to witness at the passing of a tube-like creature at the very bottom of the sea once. A lake was no big deal – especially to get Bandersnatch back. The final task had been the doosie though, the cup that had transported him to that graveyard. Crouch had obviously done that before he'd been Kissed. Death had apologised for having to take Diggory away, and Harry had apologised for not having brought the dagger so that Death would be able to take some more of Riddle away. At least he got to help Fred and George start up their joke shop.
Fifth year had been ... fun, actually. Alright, so having a Ministry 'spy' at Hogwarts – and an arrogant one to boot – hadn't been great, especially since she resembled a toad, but he'd quickly formed the Practical Defence Club to counter her, and when the pink, two-faced woman had given him detention for putting up a notice in one of the halls giving time and place for a meeting of the PDC after she'd refused permission for this particular group's reformation, well, that had been really fun. She'd handed him a quill, and he'd Remembered what it was the instant he held it in his hand.
"These were made illegal after World War One," Harry informed the woman politely. "What would the Minister think if he knew you were not only in possession of one, but forcing under-aged witches and wizards to use it?"
"Your lines Mr Potter," Umbridge had said, some of the sugar shaken off the edge of her voice.
"Dolores Umbridge," Harry said, standing up and putting the quill down, his green eyes flashing blue in their depths. "You will write lines until the words have made an impression on your very soul. You will write: 'I must not think I am superior, because I am not.'"
She had too. Her classes had been cancelled in favour of the PDC for a while because she was still writing – without having stopped for anything – still when school broke for Christmas, when they came back after holidays, and eventually had to be removed to Saint Mungoes. Snape took over teaching the regular classes then.
Sixth and Seventh years were a bit of a blur. Harry managed to get to all of his classes, but only thanks to the gifts that Time had given him, and the skills he had inherited from Death. After all, he was fighting a war at the same time – a war in which having Miss Sto Helit and Bandersnatch beside him when he fought frightened the Death Eaters more than the threat of Dumbledore. A portent of death and a very pale someone dressed in stylish black and carrying not only a sword so sharp that it was invisible to the naked eye, but the ever-dramatic scythe as well? Harry chuckled at how some of them pissed their robes where they stood.
Riddle managed to hold it together for a while, but he crumbled when Death himself stood before him, and Harry told the Dark Lord that all of his horcrux had been destroyed. When Time arrived and lay hands on Riddle, the wizard abruptly became very, very old, and very, very weak. Harry struck the Dark Lord with his dagger, and Death swung his scythe.
Harry disappeared after that. Not even Hermione, his closest human friend, could find him. Ten years later, a man with bright green eyes – and several sets of coloured contacts for when he felt like having pink eyes, red eyes, purple eyes, blue eyes, brown eyes or golden eyes – black hair that had been bleached and dyed in places, a large old dog at his side – as well as a much smaller puppy of the same breed trailing behind, and a raven on his shoulder – a gift from when he was seventeen – appeared at the gates of Hogwarts.
"I'm here to see the Headmistress," the man told the gargoyle, deep within the castle. "I'm the new teacher."
The gargoyle stepped aside.
"Well Banders," the man said, stroking the old dog as the walked up the stairs, "we're back again."
The old dog wuffed in agreement, then whined softly, as though asking a question.
The man chuckled in response. "No my friend, you'll have the very best in your declining years. I just couldn't bare to leave you behind. Besides, I expect you to help me keep the students in line."
The old dog seemed to wheeze a chuckle, while the puppy behind yipped and wagged her tail.
"Yes Queen Mary, you too," the man chuckled.
"Mr Potter?" Minerva MacGonagall was surprised to see the boy, now man, standing in her office.
"Actually, it's Addams now. Hello Headmistress," Harry answered with a smile. "I've come to apply for the position of Defence teacher, and History teacher."
Minerva frowned. "Professor Binns still teaches History of Magic," the old woman said.
"And I'm sure his students still fall asleep in class," Harry answered. "No offence to Professor Binns, but he cannot hold the attention of the students, and he's missing out on rather a lot of history."
Minerva's frown deepened. "Can you handle the workload of taking two subjects?" she enquired. "There is a lot of work involved with just taking one for all of the seven age groups."
Harry nodded. "Perfectly capable," he answered. "You'll even see grades go up."
Minerva sighed, but agreed.
Harry modelled his History classes on the lessons he had received from Miss Sto Helit when he was little. None of the students fell asleep as they stared around at the Goblin Wars, and a great many of them discovered an enthusiasm for history that they had never had before. Defence class was more practically involving, requiring the students to all attempt to use the spells he demonstrated. Sometimes against a dummy, sometimes against an opponent, sometimes against a magical creature. As well as learning the magical side of things, Harry taught the students about the World Wars, man's first steps on the moon, and how to use weapons other than magic.
All of the staff agreed that the students had never had such high exam, O.W.L. and N.E.W.T. scores in the history of the school.
Some of the staff – and particularly Hermione, who had taken over the position of Muggle Studies professor long ago – questioned Harry on where he had been for the intervening ten years, but Harry never gave a satisfying answer. After all, they knew he'd been 'away', they wanted to know where he'd been away too!
"Just... Away, for... a while," he'd always answer with a smile. No one ever saw the Death of Rats who came to visit him sometimes.
The only other kind of answer they got was from the woman who was apparently his wife – Wednesday Addams – when she came to visit the school to spend Halloween and mid-winter holidays with Harry. When she was asked, Wednesday stated in a calm monotone that "Harry promised his first born to the Addams family when we took his godfather's case. It was just easier to have him contribute children to the Addams family this way."
"Besides," Harry added to the horrified looks of listeners when they heard this, "Wednesday and I actually love each other, loathe as she is to admit to feeling anything."