Harry landed in the Forest of Dean, checked that he hadn't been followed, put up stationary and mobile shields, and recast all his stealth charms just in case. Then, once under shields - he couldn't have done this at the DMLE, there wasn't time and the building was warded against this sort of thing - he began to cast the anti-tracking charms that would obscure his Apparition trail. He could practically hear Robards giving him grief about the redundancy, but whatever, Robards was an idiot and Harry had no idea how the man had ever, even briefly, been allowed to outrank anyone. Stationary shields were orders of magnitude harder to break than mobile shields, and could cover multiple people, but you had to pay attention to them, and you had to drop them to Apparate. Mobile shields would stick around until broken, but they were much more fragile if you were trying to multitask. He'd rather have them both. You just did not mess around when Alastor Moody was your opponent.
Paranoia soon found itself justified, to Harry's simultaneous relief and alarm, when Mad-Eye materialized with a pop just inside Harry's stationary shield, mere seconds after he'd begun casting anti-trackers, and bounced several nasty curses off of his mobile shields.
Harry yelped, dropped stationary shielding, and Apparated out of the way of a wide-angle bone-breaker hex. He bounced, halfway-nonexistent, through several dozen-meter Apparition steps while he repaired his mobile shields, dodged several more curses in the process, fixed his shields again after they started to crystallize around a few brightly colored immobilizing jinxes, and then got hit with a momentum-changer that his shield wasn't designed to block. He got knocked violently sideways, and smacked into a tree halfway through the incantation for his stationary shield. This time he'd made the shield small enough that it wouldn't be possible to get inside without breaking it, and it sliced partway through the tree he'd failed to notice, giving him less space to move than he'd wanted. Still, the shield worked, and his feet touched the ground (barely), so he wasn't going to complain. Leaning against the tree, he paused for a moment to breathe; there was no air in the space you travelled through to Apparate, and doing it a number of times in close succession wasn't pleasant if you were out of practice at timing your breaths.
(Harry made a mental note to do some drills on that, soon.)
"Harry Potter," said Mad-Eye in a dark voice, stalking towards Harry. He'd bounced a few curses off the stationary shield, noticed that they were having zero effect, and stopped. "Or should I say, He-Who-Must-Not-Be-Named?"
"Fuck's sake," coughed Harry, his voice still slightly strained from lack of air. "I am not Voldemort. Hell would he give you Pettigrew for?"
"Scapegoat," suggested Mad-Eye instantly. "An attempt to pin Black's crime on someone else so that we'll trust him again. Revenge, maybe - if Pettigrew's been alive for twelve years he must have had good reason not to want to be found, maybe he did something to annoy you. Or maybe Pettigrew's a plant, maybe he's innocent but he's got a timebomb planted in his arm, maybe he's a sleeper agent, maybe he's really guilty and he's a distraction. Maybe he's really guilty and you want us to think that means Black must be innocent so that we'll burn energy and resources rescuing him from you, and then you can use him as a spy. Maybe something more complicated I haven't thought of yet."
Okay, Harry had dramatically underestimated this man's paranoia.
"Put Pettigrew under Veritaserum," he suggested, "he's not clever enough to Obliviate himself, he'll admit to killing a dozen Muggles and faking his own death."
"Assuming we actually do that and assuming that's what he actually says and assuming he hasn't been Obliviated by someone cleverer," growled Mad-Eye, "I've already thought of at least two ways you could still be trying to fuck us over. Weren't you listening?"
"I guess I could be," sighed Harry, annoyed. "If I hated you. Which I don't. Because I am not Voldemort."
Mad-Eye's eyebrows, or what remained of them, rose. "Less than five minutes ago you painted a death threat on my office wall."
" ... fair point," admitted Harry. That had probably not been a terribly good decision. And it had been rather more emphatically violent a message than he'd planned. Maybe he should be taking more careful inventory of how the scar-Horcrux was affecting his moods. It wasn't capable of possessing him, he was pretty sure, even without any Occlumency, but it might well be nudging him into being more impulsive, more angry, more violent. He'd gotten so used to not having it that he'd forgotten that might be a problem, he'd been considering it only in terms of what Dumbledore might think. "In my defense, Peter Pettigrew killed my parents and got my godfather thrown in Azkaban for a crime he didn't commit," he offered. "I want him to spend the rest of his miserable life in Azkaban, and if I have to take the distant second choice of instead making him very dead, I am going to be extremely annoyed at someone."
Mad-Eye rolled his eyes. It was a sight to behold. "Look," he said, "I realize that tricking people into things is your second favorite thing after torturing them, but you are not going to convince me that you're Harry Potter. You don't talk like you're five years old. You don't fight like you're five years old. You don't even move like you're five years old. You might be in Harry Potter's body, sure, I heard the report about you under Thief's Downfall. But if you're not You-Know-Who I'd bet money you're one of his minions. You fight like Savage got high on black lightning. You're not Harry Potter and I know it, so do us all a favor and stop trying."
Black lightning was a magical liquid drug, the active ingredients of which were vampire venom and house-elf blood. Some people added ground-up dragon scales. Harry was not completely clear on how it was made, mostly because the one time he'd come across a recipe for it, it'd been written in a language he didn't speak, and he'd given it to Hermione, and she'd taken one look at it, made a truly awful face, and set it on fire. But he knew it was bad. But people did it anyway, if they were desperate. Black lightning sped you up, made you scarier. You could run faster and dodge faster and cast faster, and it kept you awake with an effect similar to an adrenaline rush; it made you markedly more dangerous. It wasn't a huge problem in actual duelling circuits, despite its utility, because people under the influence of black lightning were very distinctive and easy to identify: They were like sticky, skipping records, perfectly still and calm at strange intervals and then bursting into sudden, chaotic motion that was faster than any human had the right to be capable of. It was extremely addictive and highly illegal, in addition to being obvious, so you mostly saw it among career criminals, which meant the Auror Office dealt with it on an occasional basis. Fighting one was largely an exercise in shielding, because most people couldn't dodge that fast but they could wait it out. The effect only lasted for about a half hour at the high end, and people usually collapsed afterwards from the strain, physically and magically exhausted.
This was not the first time Harry had been told he came across that way when thrown into combat. John Proudfoot had noticed almost instantly, the first time he watched Harry and Ron practicing on the Aurors' training floor. There had been a somewhat unpleasant internal investigation, a great deal of confused press, and then shortly thereafter a lot of apologizing. The Auror Office had access to the country's best Healers and truth serum; it didn't take that long for them to conclude that Harry had never touched the stuff in his life and in fact had never heard of it until Proudfoot brought it up.
He really did just fight like a very talented crazy person.
But that had been several years ago and a decade and a half in the future.
"Um," said Harry. He sighed. "I suppose there is not really any convenient way for me to offer to drink Veritaserum and then repeat to you that I am Harry Potter and I have not been possessed and I have not been taking illegal drugs and so on." He tried to smile, sensed that it had come out a bit crooked. "Since you'd just hand me over to Dumbledore and he would try to send me to my family. For my safety."
"Seriously?" said Mad-Eye, sounding genuinely astonished. "Your excuse for not wanting to talk to Dumbledore is you don't like your family? Did you think I'd actually believe that?"
Tilting his head, Harry asked, confused, " ... did you have another reason in mind?"
Mad-Eye made an impatient, disbelieving noise. "No," he said sarcastically, "I can't think of any reason why the leader of the Death Eaters would want to avoid being anywhere near Albus Dumbledore. None at all."
Oh. Right. Only one he ever feared and all that. As far as anyone in this time was concerned, Dumbledore was Tom's greatest enemy. They didn't get over that until, what, 1996 or something? Harry wasn't even sure, he had been a little busy at the time being a spectacularly moody teenager. "You know," said Harry, leaning his head back against the tree again and sighing, "the really depressing thing about this conversation is that I could probably convince the Death Eaters that I'm Voldemort. It probably wouldn't even be difficult. And I have no idea how to convince you that I'm not."
"You can't," shrugged Mad-Eye. "Dumbledore's reasonably certain you can beat Veritaserum and I don't have any reason not to believe him."
Harry's eyebrows rose. He couldn't help it. You had to be a really good Occlumens to beat truth serum. "Beat Verita - me? Seriously? I had trouble blocking dreams when I first learned, how on ... earth would ... I ...," he trailed off, and sighed. "Right, right, Voldy's a master of the mental arts, right, of course." It was surprisingly difficult to keep in mind that the old Auror was talking to him with the firm conviction that he was actually Voldemort. Harry knew this, but it still didn't immediately register that that was what Mad-Eye meant when he said you. "Awesome," grumbled Harry. "So even if I could arrange, without being kidnapped and thereby dramatically inconvenienced, to offer you magical proof that I am not lying, I could theoretically still be Voldemort who is unusually good at defeating magical lie detection. And you would still not believe me."
"That's about right," agreed Mad-Eye. "You could just give up now, save us all the trouble."
"God dammit, Mad-Eye," said Harry. He considered for a long moment what his possible options were. The silence went on long enough that Mad-Eye started trying to break his stationary shield, which was very slightly concerning but honestly only very slightly. Harry had faith in his invented-fifteen-years-in-the-future protection, and he had a problem to solve. If the Aurors, and Dumbledore, were genuinely convinced that he was possessed by Voldemort and would not be convinced even by Harry's testimony under Veritaserum, he was going to have a lot of trouble just casually showing up for school in 1991. Dumbledore might not even send him a letter. They were also unlikely to accept Peter's arrest as proof of Sirius' innocence, now that Mad-Eye had observed Harry to be at fault for that (which hadn't been in the plan, but plans never worked). Although he did think it was likely that they'd still follow standard procedure, interrogate Pettigrew, and arrest him for being, if nothing else, an illegal Animagus. Unfortunately, Harry realized, if they believed he was a Death Eater this might just mean they'd assume he was a plant, and take that as more evidence that Harry was their enemy.
"Hell is this shield even made of," muttered Mad-Eye irritably.
And being able to perform magical feats previously unheard-of, like defeating an entire squad of Aurors with a single shield, was not going to help his "I am totally Harry Potter even though Harry Potter is five years old" argument. If he kept going around being totally ridiculous at everyone, they were just going to keep thinking he was Voldemort, and they would treat him accordingly. He'd probably be arrested on sight no matter how peaceable he tried to be, and Harry wouldn't be at all surprised if he found the gates of Hogwarts barred to him.
He did not like that idea. At all.
He supposed he could probably arrange for Adrian Murphy to go to Beauxbatons. Fleur's parents were an influential part of the French political system and if he asked extremely nicely, perhaps by inventing some reason he didn't want to go to Hogwarts, they could probably get him an invitation. But there wasn't really any point in doing that. Harry certainly hadn't learned everything that school had to teach him, but being older wasn't going to make him a more motivated student; he probably wasn't going to get anything more out of school the second time around than he had the first time. The only point in going to Hogwarts at all was so that he'd be on hand to avert whatever catastrophes would inevitably take place. And secondarily to re-acquaint himself with all the people he liked, he supposed,but honestly the save-the-world-or-at-least-the-school thing was probably more important, he could always find excuses to introduce himself to people after they'd graduated if he had to.
Maybe he could get a Hogwarts letter for Adrian Murphy?
No, that wouldn't work. He wouldn't be able to fool the Magic Quill. Beauxbatons might even have an analogous system, come to think of it; he'd never asked Fleur. He vaguely recalled Viktor telling him about Durmstrang's entrance exam, but he didn't actually have any idea how the French decided who could go to their school. So that idea was probably out.
... Did he need to fool the Magic Quill? No one had ever actually asked Harry for his acceptance letter at any point during the train ride. He knew where Platform Nine and Three-Quarters was, he could just show up and be all 'hi, I'm Adrian, I'm Muggleborn' and no one would - no, wait. He wouldn't be on McGonagall's list. He'd just end up standing there awkwardly at the end of the Sorting, his false name having never been called. "No, that won't work," he grumbled, and then winced when Mad-Eye made an amused noise.
"Still trying to figure out how to convince me you're five?" laughed the old Auror.
"No, I'm kind of past that point," said Harry honestly. "I'm not actually five years old and there clearly exists no evidence that will convince you otherwise." There was, of course, always the possibility of trying to convince Mad-Eye and Dumbledore that he was really Harry Potter by telling them the truth, i.e. by explaining that he had mysteriously time-travelled from twenty years in the future into the body of his five-year-old self. Unfortunately he wasn't sure they'd even believe him. The standard way time travellers in stories convinced their old friends to trust them was to produce information that they couldn't possibly have gotten except by being told it, sometime in the future, but that wouldn't work here. If Harry said something like I know about the Deathly Hallows Dumbledore would probably assume he'd been Legilimensed, because Voldemort was supposed to be one of the greatest Legilimenses who ever lived in Britain.
Information security was much weirder when mind-reading existed.
"So what are you trying to do, then?" wondered Mad-Eye, now tracing runes into Harry's shield and making disgruntled faces at it. Harry was profoundly grateful that there did not exist a way to communicate precise Apparition coordinates via Patronus, and also that no one had invented mobile phones yet; Mad-Eye would not be able to summon anyone else to their location without physically going and getting them, and that would give Harry enough time to run. In particular, this meant that Dumbledore was not going to materialize and ruin Harry's day. The shield he was using was, he was pretty sure, unbreakable by the methods of 1986 and would probably remain so until it was invented in 2004, but the Elder Wand was a power amplifier. In Dumbledore's hands, it might actually be able to overload the shield with brute force. And then Harry would end up either dead, locked in Azkaban, or Obliviated until he was five again, and a great many people would die.
"Um, basically I'm trying to figure out how to prevent a really large number of people from dying," said Harry.
Mad-Eye paused for a moment, and gave him a puzzled, querying look.
" ... basically if you guys continue thinking I'm Voldemort it's going to be really difficult for me to prevent the actual Voldemort from ruining everything," Harry explained. "Since, as you seem to have realized, he is not in fact dead."
The very slow, careful way in which Mad-Eye responded to this suggested that he'd either concluded Harry was actually insane, or he'd decided to play along in hopes of getting useful information. "In what way," the Auror asked, "is ... Voldemort who is not you ... going to try to 'ruin everything', precisely?"
Harry took a long moment to phrase his answer in a way that would not make certainty based on future knowledge sound like certainty based on self-prediction. "Voldemort is extremely unpredictable at the best of times," he said, "but the possible catastrophe modes I am imagining include, for instance, him taking over the government and making it illegal to be Muggleborn, or him taking over Hogwarts and making children fight to the death for his amusement, or him rounding up all the Muggleborns in the country and using them as fuel for some kind of really horrifying blood magic ritual, or," he tried to think of something else, and failed, "or, I don't know, I am not really that creative, I just know it'd be really bad."
"We did win the last war, you know," said Mad-Eye somewhat irritably. "We're not just going to let you - we're not just going to let Voldemort take over our government."
"You realize you won because I mysteriously defeated him by being Magical Superbaby, right?" pointed out Harry dryly. "Not because anyone in the Ministry outside the Auror Corps is competent at anything."
"Alternatively, you noticed you were losing and faked your death by setting your body on fire and possessing a small child," suggested Mad-Eye, abandoning the effort of not referring to Harry as if he were the Dark Lord. "Babies do not magically defeat powerful dark wizards by the power of Dramatic Resonance, not in real life."
Okay, as much as that was a really good point -
Harry sighed.
"Have you, by chance, ever met my mother?"
"Why on Earth would I - oh, you mean Lily Evans," said Mad-Eye. He evidently was having the same problem with the pronouns as Harry was, except in precise reverse. "Evans was a good kid. Too good for Potter and Black, but they knew it, what more can you ask. Very talented witch, you murdered her in cold blood and then possessed her son, are we going somewhere with this?"
"I," said Harry, "did not actually do anything to defeat Voldemort. All I did was exist, and my mother, the brightest witch of her age, defeated Voldemort at the cost of her own life, in order to protect me. And then, of course, when they found everyone in the house dead except me, everyone assumed that something very mysterious and dramatically resonant had happened, because no one wanted to admit that a Muggleborn witch could have defeated the Dark Lord. That happens in real life all the time, Auror Moody."
There was a long silence.
"You're surprisingly good at not using the word 'Mudblood'," observed Mad-Eye, rather quietly. He'd stopped trying to break Harry's shield, possibly because he'd run out of things to try. Possibly because he'd just realized it was possible he hadn't thought of everything.
"Of course I am, my mother and my best friend are Muggleborn, I would never," said Harry. He rubbed his temples. "Look. I'm not five years old. You know I'm not five years old. It's blindingly obvious that I'm not five years old. But I am Harry Potter and I'm not possessed by Voldemort and I don't mean you any harm," he said. "If I told you what actually happened to me you'd think I was insane, but mainly I'm considering the information classified not because of that but because Voldemort is smarter than me. If he found out this thing was possible, I'm concerned he might be able to figure out how to reproduce the effect, and I cannot possibly overstate how bad that would be. So I'm working under as much conservation of information as is possible, and I'm going to continue to do that. If you try to find out by force I will Obliviate myself, and I am not very good at Obliviation, so I will probably just end up actually five years old and then a lot of people will die because I didn't save them, so please don't do that."
There was another rather prolonged silence.
Mad-Eye said, curiously, " ... your best friend?"
"Classified," snapped Harry, who had exactly no desire to see Hermione hunted down and questioned by the Aurors.
Mad-Eye's eyebrows rose. "Uh-huh. And what's the deal with Black?"
"Entirely innocent," said Harry, "and technically not even a criminal, Barty Crouch never actually charged him with anything or had a trial."
"Uh-huh," said Mad-Eye again, rolling his eyes (different directions), "so you expect us to just take him right back and give him a badge and trust him with our secrets so that someone else can die like the Potters and the Longbottoms and the Boneses, right?" His voice was very bitter. Harry thought it was interesting that he'd included the Longbottoms, who were technically not dead. Although of course they were nonexistent for all practical purposes, aside from making Neville's life really depressing, so it was reasonable to consider them to be just as dead as Harry's parents. Harry was suddenly extremely curious what would happen if he located the Resurrection Stone and asked it to bring him the shades of Frank and Alice Longbottom. He made a mental note to try that and then went back to the question at hand. Paranoid Auror saying sarcastic things about how ineffective his attempt to ingratiate his spy into the Auror Corps was.
"Um," said Harry, "no?"
"No?" inquired Mad-Eye. "No, he's not a spy? How do you propose to convince me of that?"
"No, I'm not trying to convince you to take Sirius back," Harry clarified. "You can't have him, I need him."
Scarred eyebrows rose. "Really," said Mad-Eye. "You need him? What for?"
"Aside from that fact that he's my godfather and I need someone to practice duelling with?" offered Harry. "He's an actual adult. I am, legally, a minor and it's somewhat difficult to do certain things because of that."
"That," said Mad-Eye rather dryly, "is what legal guardians are for."
"Did I mention he's my godfather?" repeated Harry pointedly.
"Why," asked Mad-Eye, abruptly, "are you even still here? I cannot break your shield, you could have finished your anti-trackers and been gone some time ago."
That was also a really good question. Harry considered it. "Because," he said, "you're a genuinely good person and it makes me really uncomfortable to know that you think I'm evil. So I'm kind of holding out hope that I can convince you I'm not."
The old Auror sighed heavily. "Against my better judgment," he said, "I do actually almost believe you're telling me the truth. I don't know what you want from me if that's the case. I cannot let you go; you broke a man out of Azkaban, stole two of my finest Aurors' wands, and nailed a death threat and a person to my office wall."
"Can't I plead ignorance because I'm, you know, technically a small child?" said Harry, unable to help his flippant curiosity. "Surely you can't charge me as an adult?"
There were a few beats of silence, and then Mad-Eye Moody burst out laughing.