Okay, so, like, KyōjinTale is kind of crazy, and recently i've been thinking about, like, couldn't it have been EASILY avoided if certain people didn't make some certain dumb decisions?
I'm not sure if any of you have thought of that, but I assure you that without understanding their true motives, you can't understand why KyōjinTale is so sad.
#1: The 'Deal'.
If you really think about it, the 'Deal' with Flowey that Frisk makes isn't a deal. Flowey's True Motive for the 'Deal' was to get Frisk to bring him back to Asriel form without giving them any sort of payment in return, so he just said 'in return you get to have your fun'.
You may wonder why Flowey would do that, but in the Genocide path of Undertale you can probably get the idea that Flowey does NOT enjoy being emotionless, so, being emotionless, he wanted to be Asriel again but didn't want to do anything for Frisk in return.
#2: Frisk's misconception
Now, Frisk didn't really MEAN to start killing people. Quite the opposite, in fact, but from the Genocide runs that they've done, Sans has taught them that a promise is a promise. They say their 'Deal' with Flowey as a promise and decided they wanted to keep it, thus they killed people.
I'm pretty sure you remember what made Asriel go crazy. Frisk blackmailed him, saying that if he didn't reveal his father's hiding place, they would kill him. And Asriel already knew what would happen to his dad if he DID reveal him, so eventually he decided to... wait, what? Why would any sane person decide to kill their own father to make sure they didn't die/their father died some other way? Well, it has to do with two things. First, time. If Asriel had only 5 - 10 minutes to think about it, he'd probably come to the quickest conclusion which is to lie to Frisk. But since he had so much time, he probably eventually decided that plan wouldn't work and rejected it. After a bunch of rejected plans, he eventually came upon the crazy one. That's the second thing; Pain. Yes, Pain. The pain of Sans dying without Asriel being able to save him. The pain of Sans saving Toriel from demise without Asriel being there to save either of them. The pain of his best friend going insane. That was a lot of pain.
If you were told your best friend went crazy and tried to kill your Mom and ended up killing another one of your friends, I think you'd feel a lot of pain, too.
Anyways, he killed his own father for the pain of it. i know it sounds weird, but he did. He was hoping the lesser pain of killing his father would mask the greater pains. I know it's weird to say killing his own dad is less pain, but he was in control of it. He wasn't in control of Sans dying or in control of Frisk going insane. Killing his father seemed to sooth those pains somehow.
#4: Asriel CONTINUED killing?!
Yeah, I know, right? It's weird. Why would he continue? Well, it's, again, to mask the pain. He still felt bad about everything, and somewhere inside, something was telling him that it was fun to kill(Flowey did ;3). Also, Asriel was getting revenge on Frisk. So all in all, it seemed to fix his life temporarily, so he decided to kill again.
But why would he kill his mom? Well, he knew Toriel did still care about Asgore, and now that he was dead Asriel knew she wouldn't exactly be happy. Especially if she heard that Asriel himself killed Asgore. So Asriel decided to act innocent and then end Toriel's life before she heard about it. Another bad idea, but it did work, didn't it? It also made Frisk very unhappy, and Asriel enjoyed that, then killed more people to mask the pain even more.
Why did Flowey take over? Well, after the entity of Flowey came back, he wasn't very happy about sitting there, so once he got to call the shots, he did. He also enjoyed torturing his living self, AKA Asriel.
Flowey enjoys torturing people, whether it's humans, monsters, or, perhaps, the readers of the story. So he attacked with Asriel's own body, because, honestly, he didn't care about it.
I'm gonna skip ahead and get to the RESET button corrupting, then the timeline splitting.
Now here's the deal. The timeline was a Pacifist timeline, right? And the first sort of glitch that happened was Asriel not breaking the barrier, and instead staying as Asriel. But it wasn't that bad. But then, Frisk killed Sans. He was the last 'Boss' of Genocide, and he just died? He's not supposed to be able to die outside of Genocide. Then, Asgore died, then Toriel. After enough deaths, the RESET button stopped working, and the Game frantically tried to fix it so Frisk could save the timeline by Resetting. Even after Frisk was dead, the Game was still trying to fix it, but it forgot about the rest of the timeline, so it began breaking apart.
Here's the weird part.
Flowey said the reason the timeline was breaking was because there were two 'Asriel''s in physical form. He thought he was right, he just wasn't.