A/N: okey so here we go. I haven't published anyhting in ages, and this has been sitting on my computer since before Cursed Child came out, so in this story, you can assume that Cursed child didn't happen.
Albus is thirteen, Lily is fifteen and James is sixteen years old. They are all standing in Hermione's office, having sneaked in to have a look at a time-turner. Hermione has explained to them that time-turners are extremely dangerous, and one is best off leaving time the way it should be. The problem is that they are far too curious not to sneak in to test it, even though the risk of getting caught is quite high. They open all the drawers in Hermione's desk and finally find it in a small pouch in one of the lower drawers to the left. It was Albus who found it, and James immediately tried to snatch it from his younger brother. Albus, knowing his brother well, knew what was coming and stepped to the side, trying to avoid James' long arms reaching.
"Gimmie that!" James said.
"No, I found it." Albus protested.
"And it was I who came up with the idea to find it, so it really should be me who gets to handle it first. Besides, I've actually read about time-turners, I know about them." Lily argued. Both James and Lily gripped the thin chain, each hoping to jerk it out of the others' gripps. As all three of the siblings pulled at it at the same time, the chain broke, and the time-turner fell to the floor, shattering into a thousand pieces. The three siblings fell quiet, all knowing that their childishness could cause a catastrophe. The shattered pieces of the time-turner started glowing with a bright, yellowish glow that did not bode well. They didn't know what to do or say so they just watched the glow becoming brighter and then suddenly going out, taking the other light with it as well. Standing in complete darkness, they slowly regained their wits, and James, not having lost his grip on his wand, muttered 'lumos' and the tip of his wand started glowing, lighting up the room. That's when they knew that something really had gone terribly wrong, because they were no longer standing in Hermione's office. Instead, they were in a wide corridor that looked very much like one of the familiar corridors of Hogwarts.
"Where are we?" Albus asked, directing the question at his sister since she had just expressed that her knowledge of time-turners far surpassed his and his brother's.
"I don't know, it looks like Hogwarts, but as far as I know, one can't get transported in space by a time-turner, only time." Lily answered, looking around to see if it indeed was a Hogwarts corridor they were standing in.
"Well we didn't really 'use' it the conventional way, it is entirely possible that shattering it has strange effects such as moving us to Hogwarts." James pointed out.
"Why is it so dark? Is it night?" Albus wondered. "I mean, it was the middle of the day, just before it broke."
"Well, a time-turner does transport one back in time, so yes, it is likely night." Lily said, trying to be as logical as possible.
"So what do we do? We can't stay here, and how are we going to explain to anyone how we got here?" Albus said worriedly.
"Let's go to our common room first, we can explain things to our friends." James said, not sounding worried at all. "Then we can go to Hogsmeade in the morning and get the knight bus back home, and noone will know we were gone. We'll pretend that we don't know where Hermione's time-turner is if she notices that it is gone."
"Yeah, cause she will totally believe that you had nothing to do with its sudden disappearance. I mean, you never cause any trouble at all." Lily said sarcastically. "Well, I suppose as long as she doesn't suspect me it's alright." she added, smiling at him.
"Hey, that was uncalled for! And besides, as you pointed out, this was all your idea!" James protested.
Hey I know that we are in Hogwarts, but do you actually recognize this hallway? Do you know which floor we are on?" Albus asked getting the others back to the issue at hand. None of the others knew exactly where they were (a lot of Hogwarts does look very similar after all) but they decided to simply pick a direction and walk until they were somewhere familiar. After a few minutes of walking they Lily finally spotted a portrait that she had seen before, and was able to lead them in the right direction.
When they reached the portrait of the fat Lady, James said the password, and was distraught to find that it had been changed.
"What do we do now? The fat lady will never let us in without the right password." James asked.
"I don't know, it was your plan." Lily answered.
"Can't we just go straight to Hogsmead? We'll take the nightbus home right away and just make sure not to be seen until we walk into Hermione's office." Albus suggested. He didn't really know why his brother wanted to go the the common room in the first place, since that would only make it more likely that they were exposed, but he had decided not to argue so they could get going faster.
"Good thinking, we'll just use one of the secret passageways out, and then head straight home." Now having a new destination, they all started walking again. They decided to use the entrance behind the one-eyed witch, not wanting to disturb the whomping willow without needing to. Suddenly, there was a light behind them, and before they had the time to put out their wands, two Gryffindor prefects rounded the corner and saw them.
"You there, stay where you are. Why are you out of bed at this late hour?" asked one of the prefects. He looked a bit like their dad, with dark hair growing in a completely uncontrolled manner, except he was Lily's or maybe James' age, and his eyes were blue. The other prefect was a girl of the same age, with auburn hair and green eyes. None of the siblings had any idea who they were. As the two prefects drew closer, confusion became visible on their faces.
"Who are you? You do not belong here, although you are the right age." the girl said, clearly as confused as they themselves were.
Deciding to tell the truth right away, Lily said "I'm Lily, and these are my brothers, James and Albus." pointing at her brothers in turn. "Potter." she added as an afterthought, realising that these people might know their last name because of their rather famous dad. He had stopped one of the darkest wizards of all time after all.
"Very funny, we will find out who you are, you know. It will be easier for all of us if you just tell us." the boy said, obviously not amused by what he thought was a poor joke.
"But she was telling the truth, we are the Potters." Albus said.
"I am James Potter, and I know my family tree well enough to know that there aren't any others named James. Or any named Lily or Albus in our generation for that matter." the prefect said irritatedly. That's when it started to make sense to Lily.
"Wait, you are James Potter, as in Prongs?" Lily asked. Not waiting for a reply, she continued. "and you are Lily Evans?" she could see in his eyes that she had guessed correctly. He was probably wondering how she knew his nickname that only his friends used.
"Who are you?" Prongs asked softly.
"We... we are..." Lily said, not knowing how to finish.
"your grandchildren." James filled in, having come to the same conclusion as Lily. Somehow, they had jumped back not only a few hours but a few decades.
"What do you mean, you're our GRANDCHILDREN?" Prongs exclaimed at the same time as Lily Evans said "what do you mean, you're OUR grandchildren?"
"Look, we aren't sure exactly what happened, but basically we shattered a time-turner by mistake, and suddenly we had gone backwards in time several decades. We're from the future, and in that future, we are your grandchildren. I know that it is a lot to take in, but we think that this is just as strange as you." Lily explained, knowing that lying now would get them nowhere. They had started with the truth, now they had to stick to it. Lily Evans just looked at her as if she had just sprouted wings from her ears, and Prongs looked thunderstruck.
"I don't believe you." he finally said.
"We'll have to convince you then. We know some things that might convince you." James said.
"We know about Prongs, Padfoot, Wormtail and Moony. We have used the Marauders map more times then I can count." Lily said.
"The Map!" Albus exclaimed. Having just realised something.
"What, do you have it on you?" James asked.
"No, but it will tell them for certain who we are. The map doesn't lie." Albus answered excitedly.
"Do you have it with you? It would make it easier, then we wouldn't have to convince you of our names at least, and you know that if we were lying about them, the map would reveal our real names." Lily said, realising at once that it would go a long way to convince Prongs.
"What are you talking about? What map? And what do you mean you know about Prongs, Padfoot, Wormtail and Moony? Lily Evans asked sounding angry. The siblings hadn't realised that she didn't know any of those things yet. The siblings turned to Prongs. They all knew that it had to be up to him if he wanted to tell her or not. He looked uncertain, which was understandable. In the end, he took the coward's way out (very un-Gryffindor of him!).
"I'm going to get the map, you all stay here." he said, turned on his heels and, after one last long look at Lily Evans, walked away towards the Gryffindor common room.
"What is this mysterious map that will inform us of your names?" Lily Evans asked again, but this time she didn't expect an answer.
"Sorry, but it's not really our secret to tell. When James gets back, he will probably tell you, but it's better coming from him." James said.
The next question was asked with more hesitation, as it was the more important of the two. "Are you really my grandkids?" She finally asked, tentative.
"Yes, we really are. There are many things about this whole thing that are very confusing, and of which I am unsure, bit of this, there can be no doubt." Lily answered her grandmother softly. "I understand that it might be hard to accept it, but it's the honest truth." Lily Evans swallowed, but stayed quiet as she pondered the implications if their story was true. She also tried the figure out an alternative, more plausible story (one that didn't have her marrying Potter) to explain what was going on. The trouble was that she was finding it increasingly difficult to do just that. The siblings obviously knew secrets about Potter that no one was supposed to know, yet he didn't even recognize their faces. Also, why would they not go to Hogwarts? And why would they pretend to be the grandchildren of people their own age? But there were even worse things to consider. The youngest brother, Albus, (was he named after Albus Dumbledore or was it just a coincidence?) looked quite a lot like James when he was a couple of years younger. She didn't know what to think of it all, but it seemed very unlikely that it was a bluff that Potter was in on, as not only would it have been too tasteless and cruel even for him (not to mention too bizarre) but it would also require him to be a good actor. All that meant that the siblings story was looking more and more plausible the more she thought about it. If the map that Potter had flead to get really could somehow inform them of the real names of the siblings, that would almost settle it for her. But why would they suggest something that would expose them as liars?
After a quarter of an hour or so, Prongs returned. He was not out of breath, indeed, he did not seem to have hurried at all, which irritated her no end. He picked out a piece of seemingly blanc parchment from his pocket.
"Only Sirius, Remus, Peter and me know about this, you can't tell anyone about it." Prongs said to Lily Evans. She looked at him and saw that he was completely serious.
"I promise not to tell anyone." She said, looking into his eyes to prove that she meant it. He took her word for it.
"I honestly swear that I'm up to no good." he said, which confused her only for a few seconds before she saw a map of Hogwarts beginning to appear. It must have been the secret passphrase. Well, she couldn't claim to be surprised about that. Prongs quickly found their location on the map, and right where they were standing, the names Lily Evans, James Potter (twice), Lily Potter and Albus Potter were written. Prongs looked shocked.
"I… the map doesn't lie. They have to be telling the truth about their names." Prongs said, confirming what Lily Evans already suspected.
A/N: so there it is. What did you think?