The first chapter is a bit shorter, just because it's supposed to act kind of like a prologue.
If it's a scene set before the main events of the story, then it's a prologue.
Not to mention – and I'd hate to mini-mod here – but this rule exists for a reason:
While there is technically no minimum on length for One-Shots and prologues, all chapters must be an absolute minimum of TWO PAGES long on Microsoft Word, Arial font, size 12. Exceptions may be made if the chapter is exceptionally well-written and gets the job done.
Yes, that includes any chapter labeled "chapter 1." So creating a prologue instead of a chapter 1 that's "supposed to act kind of like a prologue" helps you avoid the shady business of having to deal with a mod.
But more than that, yes, it's quality control. Usually, a chapter that's extremely short is very rushed and doesn't have much substance to it. While, yes, drabbles exist, those are done by very skilled authors who know how to say a lot in a little amount of space. If you're trying to start off a story by jamming everything into literally two paragraphs, you're going to create an unfinished feel to your first chapter. (As in, it feels like you stopped abruptly, like you forgot to finish the chapter. Yes, cliffhangers exist, but there's a difference between creating a cliffhanger and creating something that feels like you abruptly hit the breaks literally a second after you started, if that makes sense.) That's not going to draw in an audience because it ends up feeling too jarring, like there should be something else that the chapter doesn't deliver. Not to mention it also feels lazy. Even prologues should be more than two paragraphs long for exactly this reason.
Speaking of paragraphs, remember that forum programs strip away all indents. Don't ask why; they just do. So although you indented your second paragraph, your post looks like a wall of text instead of proper paragraphs. This is why, to get around this, most fanfic writers will hit the enter key twice between each paragraph to create a blank line of space. That way, it's easier for an audience to read. It allows their eyes to focus on only chunks of text, rather than to have them survey the entire chapter all at once.
That said…
“Nathan! Nathan! Get back here this instant! NATHAN!”
As ridiculous as it is (No, seriously, I want to be on whatever Game Freak is on perpetually.), you know that his real name is Natural Harmonia Gropius, right? I only ask because when you're doing a history fic, it's always important to start off by establishing just how true to canon you're going to be. The reason why is because people who read history fics are usually fans of the central character. A history fic, after all, basically
expands upon canon, rather than throw it out the window, and that's a huge part of the appeal to them. They dare to ask questions that remain unanswered within canon, which is both ballsy and incredibly creative. So by starting off the fic by saying this is N's backstory while calling him by a rather generic name beginning with N instead of the one he's given within the games tends to send off a bad signal to the reader. I'm not saying that your story is automatically bad just because you decide to make Natural Harmonia Gropius something he wasn't actually born with (and to be honest, I wouldn't blame you if you did), but it
does make me wary. As a result, readers like me would probably instinctively take an inordinately closer look at how canon is used in the fic as a whole, which may not be the best reaction you'd want coax out of the audience.
instead hurdling over the 3-foot fence
Nitpick tip: Spell out all numbers from zero to ten. There's crazy numbers of schools of thought who will all argue whether or not you're supposed to spell out numbers after that, but it's really safe to assume that under ten should be in words, not numerals.
Adrenalin pumped through his veins as he flew through the forest, avoiding low-hanging branches and nimbly jumping over roots as he followed a memorized route to his secret meadow.
While I normally don't care about whether or not people pull misplaced modifiers (because I'd be a hypocrite if I did), it
does get awkward at times in your writing. In this case, it feels like you forgot you were writing a dependent clause (i.e., part of speech attached to a train of thought that can stand on its own as a full sentence) partway through it and attempted to create half of another complete idea. To clarify, it feels like you're trying to write more than one sentence here thanks to the fact that everything after "as he followed" is talking less about the fact that he's running and more about
how he's doing it. It feels like a completely different subject, and that's because the dependent clause is so wordy the sentence loses track of what it's about anyway. Or to put it in even simpler terms, you should always avoid making the dependent clause longer than the independent clause. If the former is longer than the latter, then the point of the sentence gets lost.
In this case, I would suggest either of two solutions. The first one is to chop this up into two sentences, maybe by ending the first one after "forest" and then continuing on to the second one (because it transitions from one idea to the next as I've said earlier). The second idea is to take out the part about memorized paths completely, considering you could probably get away without mentioning that part. For the latter, the readers will most likely understand he has a secret place in the woods when they see how he reacts to it and how his father fails to find him there, so that's at least plausible. The former is workable too and avoids being vague. So either one is up to you.
Everything will be alright, so long as I have Dekanox with me.
Speaking of being vague, remember how I said that very short chapters leave the reader feeling as if the installment is incomplete? That's the feeling I get here for two reasons:
1. We're never given a hint as to why Nathan was (literally) running away from home. We don't know what the fight was about, why he was crying, or anything. We're just informed that there was drama. That's a lot less effective than showing us the tail end of his troubles at home (i.e., before he ran away, rather than the exact moment that he did) or flashbacks to the argument/drama at home/whatever-that-happened. Right now, all we know is that he's crying, but we don't exactly know why. For all we know, it could be because his father just told him he couldn't have a cookie, and that would make him a less-than-appealing character, to put it lightly. Either way, not showing us even a bit of the drama or dropping hints as to what happened makes him seem a little on the emo side, even if he
is a kid. Like, is he going to cry at the drop of a hat? Is he going run off in a huff at the slightest sign of trouble? We're inclined to think so because we have little reason to believe that the thing that caused him to run off crying in this chapter was actually that big of a deal (for a kid or otherwise).
2. Dekanox? Is that Darumaka's name? A shiny device he has? Some kind of special technique that protects him at all times? Never just mention a term that would be unfamiliar to a reader. Always introduce it by defining it for them within the fic. For example, a reader can look up Darumaka without a problem, but they can't look up Dekanox. We're led to guess that it's Darumaka's name, but we really don't know for certain what it means or why it's significant to either character. Don't have readers guess about the simple stuff that they should know because it's your job as a storyteller to give them that information
clearly. This goes especially for the first chapter. If you give a reader any indication that they're going to be bombarded with terms and names that they'll never get clear definitions for, they'll end up feeling as if they won't be able to keep them straight. The less they can keep straight, the more inclined they'll be to hit the back button because it'd take more effort than it should to work through a story.
Actually, let's take on a third point:
3. A Poké Ball fell out of the sky, and that didn't get a reaction at all? Where did the ball come from? Why is Nathan hugging what came out of it like a teddy bear? What gave him any impression that it's not going to hurt him? Keep in mind that kids are a lot smarter than teens and other young writers tend to make them. They can get suspicious, and they will ask questions. They will not, for example, go up to random strangers and hug them (unless their parents' abilities to raise children leave a lot to be desired). However, in this example, it's a lot like having a kid go up to a chainsaw and not only name it but also hug it while pulling on its ripcord. Kids are just not that stupid.
So, let's say that Nathan knows this Darumaka. That still begs the question of why he didn't react to its sudden appearance besides hugging it. A Poké Ball fell out of the sky. He must have noticed it, either because it would have given off a light while releasing Darumaka or because gravity would dictate that it'd be somewhere nearby. And even if Nathan hadn't noticed the ball, Darumaka suddenly appearing before him would mean that someone else is close by. Remember, he's running away from his father (apparently). Wouldn't he at least react with caution because having a Darumaka pop up would mean that there's a human nearby? Wouldn't that give him the impression that he's about to be dragged out of the clearing at first? Why wouldn't he check to see if anyone else is watching?
And besides that, let's say that he didn't see the ball, that Darumaka wandered through some underbrush or something to meet him, and that Nathan assumes the thing is wild. Why would his first reaction be to hug it? (I'm also assuming Darumaka is well-trained and wouldn't attack or react to Nathan; otherwise, that would call up a whole host of
other questions.) Think about it for a moment. Sure, maybe when you were five or something, you might have wanted to chase after wild animals and pet them or whatnot, but I'm also assuming you didn't think that they would react like teddy bears. I mean, this is a living animal, so it's pretty logical to assume that it's going to move or react to you, regardless of how old you might be. And not all reactions are good. Besides that, Nathan was crying and generally in a terrible mood before this. Wouldn't he react a little more slowly or carefully before accepting another living creature in his circle of woe?
In short, it's always good to see someone try to tackle a character's backstory. History fics can be wonderful and fascinating things if done correctly. However, it's difficult to say how successful this one will be because of how abrupt this chapter was. It really goes to levels I'm not sure you intended. A lot of it is vague – even for a first chapter – and the drama that could be here isn't there. It just feels rushed and too compact, so it's difficult to feel something for Nathan or to grasp just how terrible his life is. All we see is him crying for no reason that's apparent to us shortly before he hugs a Darumaka that may or may not be one of his few companions.
Given that this is the first chapter (no pun intended) of N's life, you really should consider drawing it out a bit more. You'll really want to capture the part of N's canon backstory that said he was trained from a young age to believe humans were despicable (or otherwise not trustworthy) and that Pokémon are the only kind and trustworthy beings he can befriend. In order to do so, you'll need to heighten the drama, and the way you do that (without making your fic seem ridiculous or over-the-top) is by showing us the drama, not simply telling us that it happened (or not mentioning it at all). Show us, for example, his father doing something so terrible that it causes him to run out of the house crying. Show us Darumaka being gentle with Nathan and making him believe that it's a lot more trustworthy than his father. Bring out the drama and heart-wrenching moments by displaying the way characters interact with each other. By doing that, the drama feels more natural, and it's easier to connect with the characters and invest interest in the story as a whole. And unfortunately, with N's backstory being what it is, the drama is really going to be something that you can't entirely avoid.
Tl;dr version of this review: It's not exactly bad, but there's not really too much here to convince a reader dropping by that it's amazing, either. It just goes by a little too quickly. However, the concept has a lot of promise; it'll just take a lot of effort to bring it out.
Good luck!