It was the second-to-last day of the term. Harry Potter's third year at Hogwarts started horribly, but he personally thought it ended rather well... If you excluded that his godfather was still a kill-on-sight fugitive and that a loyal lackey of Voldemort was now probably out there, searching for his master. Still, compared to the two previous ones, you could even say it was a fairly normal, danger-free year... If you completely forgot the hordes of dementors and a certain near werewolf experience, of course.
Harry did like studying magic, but he wasn't naturally curious and knowledge-hungry like Hermione. Whether this was due to years of conditioning by the Dursleys, or a desire to not stand out too much - well, not stand out much MORE, at least, with the whole Boy-Who-Lived nonsense - Harry was usually perfectly happy with knowing just enough to pass his classes. Still, this time, there was something nagging at him. Something he'd like to do, to find out, and a prime opportunity, possibly his last in life to do so, would be gone when the term ended.
After all, rare, ministry-controlled magical artefacts didn't often end up in the hands of third-year students. After their double death-row-prisoner-liberation adventure, he asked Hermione about more details about the Time-Turner she was borrowing to attend all her classes this year. He was informed that there was a very limited stock of them in the world; they weren't impossible to create, but very expensive and quite dangerous, so their numbers were kept to a minimum. The school had some sort of a contract with the ministry, which lent it up to two Time-Turners per year, in highly justified cases. The fact Hermione was allowed one was just a testament that she was held in extremely high regard by the teachers - they were usually only given to NEWT students which were taking all or nearly all of the subjects.
So, Harry had no doubts that it was quite likely the last time he would ever be seeing one. What he wanted to find out and do was something Hermione repeatedly warned him about during the aforementioned escapade. From what he was told, wizards often used the time turners irresponsibly and ended confronting their past selves, which in turn often attacked, thinking they were encountering a polyjuiced impostor or something of that nature.
Sometimes, that mishap ended in killing their future selves, which was the a slightly better of the two scenarios, as most understood not to repeat the mistake of going back in time, and the inherent magic of the Time-Turner fixed the slight paradox in the timeline, even making the dead time-traveller's body disappear.
What was worse, however, was if the opposite happened. Perhaps the time-traveller started to defend himself from himself and either got a bit too happy with the curses sent in retaliation, or some sort of accident happened and their past self ended being the one killed. The inherent magic of the Time-Turner was still all-too-happy to fix the resulting paradox, but since it wasn't possible to bring anyone back from the dead, the easiest way to do that was to make both the dead and alive instances of the person disappear right that second.
But, Harry was very intrigued with this concept of meeting himself. That was surely something very few people could claim to have done and it definitely would end up being an enthralling experience, right? He also had a plan to make sure he wasn't attacked by his past self when he attempted it.
Still, he had to convince Hermione. As he gathered arguments and confidence to break this to her, the term was rapidly coming to a close. On the final day of classes, it was time. While Ron was occupied with destroying some fellow Gryffindors' chess strategy, Harry excused himself from the common room and walked towards the usual gathering spot of Ravenclaws and Hermione - the library. He easily spotted some bushy hair from the entrance and made it towards her. She was hunched over the summer homework already, which slightly amused him, but he knew she'd be better for it at the start of the next year - he'd probably have to finish the final pieces of it in a rush during the train journey or before first classes started. Either way, he (quietly, Madam Pince was on the premises, after all) started the conversation,
"Hey, Hermione." She quickly raised her head and smiled slightly,
"Hey, Harry. I thought you'd be spending your time with Ron right now." Well, she was right. Was he not so interested by this, he'd probably be that one Gryffindor being destroyed at chess right now.
"Ah, I have a question for you, actually, but I'd need to ask it somewhere more private." There were too many people in the library that could listen in on their conversation, even at this time of year.
"Uh, alright. Is it about... your doggie friend?" The question made sense. He definitely wouldn't want to discuss Sirius in public, after all.
"...Sort of." That was kind of true. The two topics were somewhat related, since he was saved using a Time-Turner.
"Well, alright. Hold on just moment, I'll gather my things and we can go." She did so, and they both left the library a moment later. Harry motioned to Hermione to follow him. He needed a place no one would visit right now. He settled on one of the secret exits from the school that caved in at some point. People who knew of the exit's existence would know it wasn't possible to traverse, and people that didn't likely weren't looking for secrets so close to the end of the year. He also picked one that was in a rarely-used part of the school. Indeed, there were no students on that corridor. When they made it inside the passageway, he lit two torches that hung on the wall and closed the entrance by covering it with the tapestry that obscured it.
"Alright, Hermione. Do you promise to hear me out and not shout?" She looked slightly worried, but nodded. He gathered up his confidence.
"There's something I'd kind of like to do and today is probably the last time I'll ever have a chance to." She didn't look less worried, but more curious, perhaps. "You have to return the Time-Turner tomorrow, yeah?" She nodded and started opening her mouth, but Harry continued;
"Er, right. So, remember when you said meeting yourself in the past was dangerous, because you could startle yourself and get attacked?" She started glaring and evidently it was enough for her to NEED to start talking.
"Yes, of course I remember. I had to avoid myself all year for that very reason. We're not doing that, it's far too dangerous!" She looked ready to retell the history of all the wizards that met their fates doing this, including all the dates and names, so Harry motioned to her to let him speak before she could.
"Okay, but, look. That's only the case if you startle your past self, right? But what if we set it up in such a way that we KNEW we were coming back in time to see ourselves?" She immediately moved in to refute him, but paused.
"How?"
"Ah, er, well, we'll just plan right now to go back in time and give our future selves a signal that it's okay to enter. That way we'll know they're coming."
"What kind of signal?" She asked, and Harry moved towards the tapestry obscuring the entrance to the caved-in passage.
"Well, how about I just push this tapestry like this?" - he pressed on it from inside with his open hand a few times, causing it to bulge - "And then, when we come back, we'll know it's safe to enter!"
Hermione didn't look particularly impressed, and after a moment, she spoke. "Well, where are we, then?" Harry frowned. "What do you mean?"
She sighed. "Well, since you did your signal, our future selves should be coming in right about now, right?" Harry mulled that over for a second.
"...Ah. Er, right." - he stuttered out, until, eventually he followed with - "Well, I guess you didn't agree to this, after all." Hermione thought for a second and rolled her eyes. "Of course not. I mean, why do you even want to do something like this?" she queried, with an annoyed look.
"I'm not sure. It just seems like it might be fun and, uh, interesting..." He tried to recall all the wonderful arguments he kept making up for the last few days, but they suddenly didn't seem very enticing after all. "Er, it'll be for, uh, science, you know."
"Science?" She raised an eyebrow. Harry looked at her pleadingly. She sighed.
"Alright, alright, already. I suppose it should be safe, though I still don't see the point. Either way, no one showed up when you did your, ahem, signal." Harry beamed at the first words, then looked thoughtful. "Well, let's agree that we enter on the SECOND signal, then, okay?" He walked up to the tapestry and pushed it again. Harry and Hermione held their breaths, and were about to sigh in disappointment, when the tapestry moved.
While they both honestly expected the sight that might greet them, seeing yourself staring back at you was startling nonetheless. The two time travellers stepped in. The older Hermione seemed to be smirking slightly, while himself from the future looked slightly peeved.
Younger Harry stared at his counterpart with a slightly opened mouth and took in all his features. His gaze was pointed at his scar when he heard himself cough.
"Honestly, I hoped that at least my own self wouldn't need to stare at the scar. I'd think I know how it looks from the mirror." - said the older Harry, in an annoyed tone. The time-travelling Hermione chuckled.
"You did that yourself, you know."
"Yeah, and I can definitely see why He got annoyed at it. Besides, it IS fun to tease."
"Er, 'He'"? - queried younger Harry, while starting to blush slightly.
"Yes, 'He'" - he heard himself reply. "Meaning the version of myself I did this session with from your perspective."
"Oh." - the first Potter replied and frowned, thinking over the complexities of Time-Travel. He heard himself sigh this time.
"He was also right. Doing this the second time isn't really that interesting."
Older Hermione nodded. Young Harry bristled and was about to protest when-
"Don't bother protesting or listing your reasons of doing this. I'm well aware of them, believe me." - Older Harry smiled slightly here.
"H-how did y..."
"I already did this, remember?" - He explained in a bored tone - "I remember what kinds of thoughts I had... quite well." Younger Harry took a second to realize what that meant, and his future counterpart smiled slightly again. "You're about to think about potatoes, by the way."
That confused the hey out of the non-time-traveller, and he started thinking what potatoes had to do with anything and what about them could cause him to think about them right now... when he realized that, indeed, he started to think about potatoes.
"But that's... you..."
"I caused you to think about them? Yeah, of course. But you did in the end."
"But then... "
"Who did it first?" - Future Harry shrugged. "Who knows. The mystery of time travel."
Young Hermione spoke for the first time.
"That is actually... rather fascinating. While preparing myself to use the Time-Turner this year, I've read a theory that stated that every time someone time travels, they create a new, alternate universe. This would certainly prove that!"
Older Hermione replied, smiling,
"But then there would need to exist a "first" universe where no one came back in time after Harry's second signal, and yet we decided to go back in time anyway, wouldn't there?" Her counterpart looked thoughtful.
"Honestly, don't bother thinking about it" - started the time-traveller Harry - "You'll just give yourself a headache".
His younger self groaned. Indeed, one was already starting.
"Well, what did you do during your 'session', then?" - he asked.
"Not much. My older counterpart was annoyed, and it was over rather quickly, anyway."
"Is... is that why you're annoyed right now?"
"Pretty much, yeah."
Younger Harry groaned again.
"Well, uh, how about we did something differently, then? Let's talk about something, or, uh, do something?"
Future Harry sighed, and with mock hope in his voice replied, "Awesome idea. Well, why don't you tell me what we could talk about or do?"
"Well, how about..." - started Harry, but nothing came. There wasn't really anything to discuss, since that WAS himself right there, and the age difference meant they knew and thought pretty much the same things. Still, wanting to salvage things, Harry finally got an idea. He didn't notice his older self smirk slightly at that exact moment.
"Okay, say, come closer?"
Obediently, the time-traveller did as told.
"Well? Did your older self do that, too?" - queried Younger Harry.
"Yes." - was the reply he got.
Exasperatedly, Harry squeaked out; "Okay, well, just try to do something he DIDN'T do?"
In response to that, the older Harry squatted.
"Well? Did your older self do that, too?" - queried Younger Harry, again.
"No."
"So...!"
"Ah, yes. Absolutely fascinating exercise." - the sarcasm wasn't concealed at all in that statement. "My older self, instead of squatting, simply moved backwards." He grinned. "And now, we're back to the 'script', as it were."
Younger Harry just sighed and looked dejected. With that, Older Harry peeked at his watch.
"Aaaand, it's time for you to go, now."
"Go?"
"Yes, back in time. It's time for you to experience this wonderful experiment from the other side." He smirked. "I hope you enjoy yourself, there."
Harry thought for a second, before responding. "We could just not, I suppose."
There, Older Hermione stepped in. "Oh, no, you will. If you don't return to the past, then the paradox will have to be resolved, and we'll end up disappearing. I don't really feel like finding out how THAT'S like." She shuddered slightly at that thought. "It was YOUR idea, anyway, so own up to it and go."
It was time for Younger Hermione to smirk slightly, and Older Harry just looked sympathetic at his past self.
"Well, we did a single spin on the Time-Turner just behind the corner of the corridor, here" - continued the time-traveller Hermione. "Go. You have about... three minutes. And remember!" She winked. "Second tapestry push."
The two to-be time travellers took one last look at their counterparts and left the caved-in passageway with a "Bye." Their older versions looked at each other.
"Well, Hermione, I must say, you were right once again." - said Harry, looking thoughtful.
"Oh?" - she raised her eyebrow, triumphantly.
"Bad things happen to wizards that meddle with time" - he quoted her words from a few days ago. "Something certainly has. First and foremost, boredom."
They snorted at that, put out the torches and started making their way towards the Gryffindor tower, hoping to get there before curfew.