Disclaimer:I am in no way, shape or form the creator of said universes. I am simply the one who decided to write in the universe of these characters.
The beginning of this is from Chapter 35 of Harry Potter and the Deathly Hallows and it is word for word, I felt like it would be a good starting point to the story.
Chapter 1:
"I think," said Dumbledore, "that if you choose to return, there is a chance that he may be finished for good. I cannot promise it. But I know this, Harry, that you have less to fear from returning here than he does."
Harry glanced again at the raw looking thing that trembled and choked in the shadow beneath the distant chair.
"Do not pity the dead, Harry. Pity the living, and above all, those who live without love. By returning, you may ensure that fewer souls are maimed, fewer families are torn apart. If that seems to you a worthy goal, they we saw good-bye for the present."
Harry nodded and sighed. Leaving this place would not be nearly as hard as walking into the forest had been, but it was warm and light and peaceful here, and he knew that he was heading back to pain and the fear of more loss. He stood up, and Dumbledore did the same, and they looked for a long moment into each other's faces.
"Tell me one last thing," said Harry, "Is this real? Or has this been happening inside my head?"
Dumbledore beamed at him, and his voice sounded loud and strong in Harry's ears even though the bright mist was descending again, obscuring his figure.
"Of course it is happening inside your head, Harry, but why on earth should that mean it is not real?"
Just as the mist was clouding over Dumbledore's face, it started to clear again and Harry and Dumbledore both looked at each other in extreme confusion. A soft crack was heard a few meters behind Harry, and both men turned around to see who had just apparated into Harry's mind. A tall man dressed completely in black was the supposed intruder and both Harry and Dumbledore reached for wands that they didn't have on them. The man walked towards the two before stopping five meters in front of Dumbledore.
In the silkiest of voices, one laced with a hidden threat of danger and darkness the man spoke, "Oh dear, not so fast Harry. You see Albus has not informed you of all the choices you have available to you."
Harry stood his ground and asked, "Who are you?! What are you doing in my head, and what do you mean by another choice?"
The man chuckled, "Well straight to the point I see. I am Death, plain and simple. I am the one in charge of making sure that the souls of people who were supposed to die are done so in a timely manner. I am in your head because I am here to gift you a boon to thank you for returning all but one of the parts of Tom Riddle's soul to my realm. You see, that man, well I'm not really sure if he can be called than anymore, was supposed to have been killed sixteen years ago, the very night your parents joined my realm. However, through the use of those disgusting Horcruxes I was unable to capture him in time, so in order to thank you for your help I am adding one more option to your list. As Albus said, you take the train to move on, to completely join my realm. You can simply stay here to go back to your reality where I am sure you will aid in the defeat of Voldemort. Or, and this is your gift, you can walk through the wall that normally takes you to the muggle world," Death said pointing towards that specific wall, "and you will be taken to an alternate universe where you can continue to live your life as and how you see fit."
Both Dumbledore and Harry looked dumbfounded at the news. Harry was the first to reply, "What do you mean an alternate universe? Who will be in this universe? Will I even be on Earth?"
Death looked at Harry for a couple of seconds before sighing and saying, "Very well, I will explain it to you in your mortal terminology. The universe works as a multiverse, which means that there are an infinite number of universes around that have similar circumstances and people. For example, some universes don't have magic but they have mutants who have gained power in one way or another, some universes have life from other planets that have reached Earth, some planets have wizards and witches just like here. In fact, some universes have magical users only outside of Earth, and some universes have creatures unlike anything you've ever seen. Some universes are in the same development as your earth, whilst some are very far in the future or quite a way back in the past. Really the possibilities are endless."
Harry was starting to understand what was going on and turned to Dumbledore and asked, "What do you think of all of this?" However, Dumbledore simple continued to stare and death without saying a word and Harry turned to Death and asked, "What happened to him?"
Death had a small grin on his face, "Simple, this Dumbledore here is obviously not the real Albus. Albus's soul has already reached my realm. This is simply the form used by your consciousness as someone who you could talk to in order to understand your own thoughts on what was going down. And so, whilst your imitation of Albus would always be very knowledgeable about all things magic and talks in riddles like the real one, Albus would never be someone who would understand physics, so your construction of him has stopped working. You can even get rid of him, try it."
So, Harry did try it and slowly Dumbledore faded out from view. Having seen the truth in Deaths words, Harry begins to contemplate the possibilities of different worlds out there, but a though stops him just as he starts thinking about it. Harry asks Death, "Wait, but won't Voldemort continue to live if I don't go back into my reality and kill him?"
Death sighs softly before saying, "No, not necessarily. Your Albus told you that because that is what makes the most sense to your subconscious. I can give you a brief overview about your world if you do go back versus if you don't. Going back would mean that by the end of tonight you end up in a duel with him and you manage to finally kill him. This leads to numerous accolades from the Wizarding World and soon enough you become the Head of the Auror division, married to Ginny Weasley with three kids. Now if you don't go back your sacrifice provides a protection similar to the likes of your mother's. Once Neville kills the snake, which happens in either reality, the war picks up again for both sides, but all the people you died for seem to be immune to anything harmful to them by the death eaters or Voldemort himself. Eventually, most of the death eaters are bound up and Voldemort is at a loss as to what to do before Neville pushes the sword into Voldemort's body from behind, which does successfully complete the prophecy. The wizarding world mourns you for a while and soon the government passes equality laws in honour of your halfblood self and your muggleborns mother. So, either way Voldemort does die tonight, and no more people from your side of the fight die tonight in either scenario."
Harry's brain starts processing the information given to him. For the first time in his life he really had a choice to not fight Voldemort and let the others take care of the issue, which really gave him some perspective on what his life would be like without having to be the wizarding world's saviour. Did he really want to become an auror and fight with the government, the same one that nearly got him killed several times, he really wasn't too sure about that. Did he feel like he couldn't leave Ginny? No, they had only dated for a few months and whilst he might've come to love her like Death says, he knew that she would find happiness either way so that wasn't a worry. He thought about Ron and Hermione and definitely felt pain and a massive sense of loss in a world without them around. However, he knew that he finally had to make a decision that would make himself the happiest. He knew that if he stayed in this world, wizards would continue treat him like a God or villain simple because of his name. He knew that he wouldn't have much privacy simple because the wizarding would never leave the boy-who-lived alone. After a few more minutes of silent contemplation Harry turned back to Death and said, "I think I would be willing to accept your boon and journey to a new world completely, how do you choose which world I am sent to?"
Death smiles, as if he knew Harry would answer that way all along, "First, I have to make sure that the alternate universe is around the same timescale as your current world so that technology is not significantly different, then I presume you don't want there to be any other wizards?" Here Harry shakes his head to confirm he doesn't want there to be others like him. "Very well, I have decided. There is a universe that is just over ten years ahead of yours, and so humans have technology that is more advanced than right now. There are going to be others with powers and there will be aliens with powers as well, but no one will have anything like the power that you have. In order to aid your conversion to this new universe I am going to increase your IQ just a little bit. This will help you learn about the new world quicker than you would otherwise. Oh, and your wand core is now part of your body, so you will no longer need a wand to do magic. All right then, walk towards the wall when you feel ready."
Harry was now confident in his decision to join this alternate world. He didn't feel ready to die, nor did he want to return. Just before he stepped into the wall to take him to this alternate world Death spoke once again, "Oh one small thing. I've taken the liberty of moving your substantial family wealth over to the new universe, and your identity will already be in the databases of your new world. Harry, a small piece of advice. Go live your life, make the most of it. You don't have to hide yourself anymore. And if you want to be a hero like a certain Hermione keeps saying about you, don't be afraid to become one. Just give yourself a mask to help you out. And go find a girl! Good luck!"
Harry steps into the wall as everything starts fading to white. He reappeared in what appeared to be an apartment. It was completely furnished with a full kitchen, one bedroom and a television in the living room. There were a couple letters on the counter table, one of which was from Death. It explained that the apartment was his and he was currently in a city called National City in the US. He also told Harry that it was 2015, that technology here was significantly more advance and that magic wouldn't affect electronics like it did in Harry's old universe. Death said that the other letters was a bit about Harry's supposed life in this universe and the other was some bank details. He recommended that Harry spend the next year getting used to the world before figuring out what he wanted to do. Finally, Death explained that he would no longer interfere in Harry's life and that Harry should do whatever he wanted to.
After taking a few minutes to digest the information, Harry takes a seat in front of the television and switches it on. The news comes up and it is a story about a girl who saved a plane from crashing into the ground, she was being dubbed as Supergirl. Clearly, there were different kind of people and aliens in this universe than his own back home. And so began the story of Harry Potter in National City.
