Board Thread:General Discussion/@comment-31619784-20170328162322/@comment-29855659-20170415190307

The ability to destroy the world is probably caused by determination. Determination is the ability to continue, no matter what happens. If sans is right, determination is a little bit like the "dark side" in Star Wars: You get more power but you become addicted to it: "and because you can do it ( SAVE,LOAD,Reset), you must" (said after sans' special attack).Also determination is "the will to live", according to Flowey's story in New Home. When Chara died he may have become some sort of "determination-black-hole", as many people seem to think that Chara was suicidal (had no will to life/determination). He "sucks" the determination out of the game and destroys the world, because it can't "continue to exist"

OR:

When Chara took over Frisk's body he gained determination. According to the libraby humans have stronger souls because they are powered by hatred and not by compassion. Frisk and the player use these to reload and to do all the other things that you can usually do in a video game. The in-universe explanation for all these "powers" is determination. If you kill and get LOVE, your ability to kill and your hatred grows. Thus grows the power of your human soul i.e. your determination. At the end of a Genocide Run Chara takes control of Frisk and their determination. They delete the SAVE. This is one of the powers you have as a player, and now, due to the determination, Chara has it to. Now they just don't reset. If they don't reset but deleted the SAVE file what is there? Nothing.

OR maybe, they just resetted by half: They destroyed what is there now but didn't reconstruct it.

OR Chara didn't reset but turned back time until before the Big Bang.

OR they are a demon and it's one of his powers (like "A Wizard did it")

I could write thousands of other theories, each of them contradicting the others, but ultimately it won't help us understand anything. As you see the problem is not, that there is no possible explanation - but to agree on one theory and to explain all the plot holes AND to prove it.

The problem with discussing this is, that we don't know anything about Chara. As I already said (although it seems to be badly phrased) we can't even be sure if Chara is a human at all. Of course I think that the whole "demon-that-comes-when-their-name is-called" is meant metaphorically. But we still can't be 100% sure. I doubt that you can call Chara human any longer, if they have ever been one. Look at the theories above. If you think about them you will probably find dozens of plot holes in every single one, which I didn't think of. Let's just look at the first one. It assumes that Chara was suicidal, which is only "Fanon" and is only implied in the game in a few lines of Asriel and even these are open to interpretation. Or the second one (my favorite) which assumes that determination enables the player to all of his abilities. Or the time travel explantion, that is VERY questionable and assumes that sans' ideas about the nature of SAVEing is right - and notably he's the only person that compares time travel to SAVEs (if you reload his judgements in the pacifist run). We need to understand the game's mechanics and the nature of Chara better before we can answer these questions. Frankly, I think we know more about Dr. Gaster than we know about Chara. CHARA. Just look at the name. It's short for CHARACTER! It's a placeholder! We don't know their name, their gender, where they lived before they fell into the Underground, we don't know their actual eye color, their age, their abilities, their unique trait (every human child in the Underground had one),their relations to others,their intentions,hobbies...everything we know comes from Asriel, who is not only a little child but has to come to terms with the fact that he spent years (and he resets, so it might be even longer) as a sociopathic mass-murderer, during which his view on Chara's philosophy might have been influenced a little bit. We have to think about all this first, before we can think about your question.

(I'm not a native english-speaker, if I made mistakes, I'm sorry)