Appeal to fiction as a possible fallacy?

Could using something that happened in a work of fiction as an argument be a new fallacy? For instance, there's a meme going round saying that two men raised Simba in The Lion King and he turned out fine, so that proves that same sex couples can raise kids.

Well, first of all, I'm not so sure he did turn out fine, because they encouraged him to turn his back on his problems instead of facing them! And secondly, anything can happen in a fictional story, whereas real life is often different, so fictional events aren't reliable proof of what's possible or plausible in reality.

A possible exception could be if a story is specifically written with a particular message or lesson in mind, such as Aesop's Fables. Indeed, there may be a possible converse to this fallacy which could be called the 'That didn't happen' fallacy. Sometimes it's the message that's important, rather than whether the story actually happened.

On the one hand, using a fictional story to support a real-life narrative can be a failure to distinguish fantasy from reality. For example, "Harry Potter can do magic, so why can't you?" On the other hand, many people use fiction as a way illustrate a point. For example, "Harry Potter couldn't have beaten Voldemort without the help from his friends. We all need help sometimes." I would say, the vast majority of "appeals to fiction" fall in the latter category, and any in the former category would border more on intellectual deficiency than fallacious reasoning.

A caveat here: Many people believe works of fiction are factual, as in the case of religious texts and cultural mythology. If the stories are indeed fiction/fantasy, then this would be a case of being factually incorrect rather than poor reasoning (how they got to believe the stories to be factual could be fallacious).

there's a meme going round saying that two men raised Simba in The Lion King and he turned out fine, so that proves that same sex couples can raise kids. 

The meme says "Two men raised Simba, and he turned out fine." Let's ignore the obvious problems already discussed, and the fact that pig and meerkat aren't "men." This is one example of two "men" raising a "child." Does this mean that it worked in this one case? Sometimes it works? All the time? It is unclear and perhaps purposely ambiguous. There are many possible fallacies one can fall victim to when interpreting this. As for the meme itself it is certainly guilty of anthropomorphism . This meme could result in a rare case of someone really thinking that this evidence for the success of same-sex couples raising children. If this is the case, I think it is so rare that a named fallacy is not justified; it might simply be the person coming to that conclusion has some kind of intellectual disability.

I'm pretty sure something like this is intended to be a little tongue-in-cheek. Thus, it's a meme rather than an argument, so no fallacies.

However, if intended as a genuine argument (unlikely); you could argue that it's a weak analogy.  Fiction does not always lend itself easily to real life, especially when not based on real people, because authors can create their own logic at odds with reality. Thus, the situations at hand are too dissimilar to compare. 

The point about Aesop's Fables is accurate, since they are actually intended as analogies.