User:AnnoyingPomeranian/Blog:Just Another Random Internet Denizen's Gaster Theory

Alright, here’s my Gaster theory (sorry it’s really long, there’s a TL;DR version at the end). Also, I’ve only played a Pacifist run (and only ever will; genocide would just be awful), so I’ve filled in some knowledge with the wiki but I probably have knowledge gaps. Also, spoilers. Here goes:

Like others, I think that Gaster is Sans and Papyrus’ “father” through the transfusion of some of his essence into two skeletons. Sans got the intelligent/creative part of his essence, while Papyrus got the perseverance and confidence. Both are also very protective of the Monsters’ world and the Monsters themselves (perhaps they were created to be guardians of sorts), and may have also been injected with Determination (the fan theory that Sans bleeds determination, not blood or ketchup, seems convincing to me).

Sans and Papyrus were Gaster’s assistants while he was the Royal Scientist (he references two assistants), and they all sought to assist the Monsters as the guardians of the Monsters’ world. But here’s the thing: I think Gaster came to be obsessed with his work, to the point of becoming a threat to the world. It seems he was obsessed with a time travel machine that wasn’t 100% operational, perhaps attempting to go back and prevent the ancient war between humans and Monsters (hence the possible translation of http://w.d-gaster.com/00000000: “This will be my final entry; I am trying to activate the machine; I must look into the beginning; the date it all started; Gaster”).

Unfortunately he couldn’t change the outcome, no matter what he attempted; each timeline ended with the tragic war and the trapping of the Monsters behind the Barrier. This is when Gaster starts to become convinced that the only way to completely prevent any Monster suffering is to prevent or eradicate their existence in the first place. This echoes some of the themes of Gerson’s conversation about an angel of death “freeing” the Monsters (though this is obviously more in reference towards genocide Frisk/Chara), but is really driven home by Goner Kid’s question (how scary would it be to see a world that exists and functions perfectly without you in it?). So Gaster tries a final experiment to undo the Monsters’ existence. This is when entry http://w.d-gaster.com/00010000 takes place (“Entry...; time has not been kind to me; I expect results in 72 hours; I just hope I am still around to witness them”). Except, for some reason (maybe because the machine has always been somewhat broken and unfixable according to Toby Fox), the only person whose existence was eradicated was Gaster himself.

Sans and Papyrus then leave the Core and set up home in Snowdin, with Sans taking the machine with him to prevent future scientists like Alphys from finding it and tampering with it. Perhaps she could have learned what it was and become obsessed like Gaster, or she could fix it and unwittingly bring Gaster back, neither of which would be safe for the world. Sans has the machine covered in a curtain: it’s obvious he’s not actively trying to fix it (in fact, the blueprints may be lying there because he was looking for a way to further prevent it from working; understanding how something works is the best way to learn how to permanently break it). He has a picture of Gaster, Papyrus, and himself with the words “Don’t Forget” as a reminder of happier times, before Gaster fell into his obsession, and maybe as a reminder to not follow in Gaster’s footsteps. By now Flowey has come into existence and has been messing with the timeline like crazy, so it seems that Papyrus has forgotten about Gaster (only he does look sad when you call him by the Core). Sans may have drawn the picture to remind himself who Gaster was, so he’d remember to not try to fix the machine.

Remember, Sans is like the world’s/game’s guardian. He’s doing this because he knows that Gaster is now a threat to the Monsters and the game itself. His “gasterblasters” have been mentioned as either being made by Gaster or made as a weapon against Gaster, and it may be the latter. Also, the Ferryman tells Frisk to “BEWARE the man who talks in hands” and “BEWARE the man from another world”; it’s apparent that Gaster is no friend. Even his musical themes are creepy and chilling, whereas the other ghosts we encounter are pretty friendly: Napstablook’s theme is jazzy, Mad Dummy’s is endearingly angry, and Mettaton’s are pretty fabulous.

When pacifist Frisk comes along, Sans first spares Frisk because of his promise to Toriel. As time goes on, he’s willing to help and protect Frisk because he can tell that Frisk may actually save all the Monsters and get them their happy ending. When pacifist Frisk does finally save everyone, Chara never appears in this timeline, likely because their (Chara’s) SOUL was finally able to find peace through Frisk’s actions and was able to pass on. In the same vein, Gaster’s ghost/shattered self may give up trying to bring himself back into the world to continue his obsessive mission when he realizes that pacifist Frisk was able to save the Monsters from suffering through different means. He finally finds peace and passes on undetected, and we see Sans as being pretty carefree and happy with Papyrus in the human world as the credits roll.

TL;DR: Gaster was Sans’ and Papyrus’ “father” of sorts, but then became a threat to the world in his obsessed mission to go back in time and prevent the Monsters’ suffering. When Gaster’s obsession proves his undoing, Sans tries to prevent Gaster from returning, realizing that his existence will threaten the existence of the Monsters and their world. Sans then helps out pacifist Frisk, knowing that pacifist Frisk will save the Monsters, and, in so doing, bring peace to Gaster’s ghost/shattered self. Gaster passes on, no one else is messing with the space-time continuum by now, and everyone gets their happy ending.