Been sick these past few days so just continuing to replay Undertale and got greatly amused at the knowledge difference between a blind pacifist Frisk and a blind genocide Frisk.
Pacifist Frisk wakes up with a voice in their head and an evil flower calling them the wrong name. Which is also the name they hear in memories that aren't theirs whenever they fall unconscious or almost die. So, weird situation to start with, but whatever. They move through the underground making friends and at the end of it all the monsters helpfully explain the whole story of Asriel and the first human. Then they go to the true lab and see the tapes and at this point even if they haven't realised who the voice in their head is they know Chara's entire backstory and who Flowey is and why they keep calling Frisk the name of a dead kid.
Meanwhile genocide run Frisk with no prior resets wakes up mad as hell and decides to make it everyone's problem. Like pacifist they get a voice in their head, an evil flower calling them Chara and some of Chara's memories whenever they almost die. Unlike pacifist the semi possession doesn't just remain verbal this time. Chara takes control to walk through puzzles or attack enemies from time to time. As this is Frisk's first run they would still have no idea who the hell is semi possessing them, but the evil flower is convinced they're Chara and judging by the voice in Frisk's head, evil flower might be right.
They reach the old royal house and Chara straight up says Hi hello its me Chara and shows Frisk around their old house. So Frisk now knows who's semi possessing them and that they used to live in this house, but that's kind of... It? No monsters to explain the Asriel backstory but instead this damn evil flower pops up AGAIN and begins trauma dumping on Frisk because he still thinks they're Chara. Which you kind of are at this point but you're also Frisk so. Rude. This flower is talking a whole lot about how he and Chara used to be partners in crime in the past and how you're best friends so now Frisk now knows that a) ghost kid aka Chara lived with monsters and b) Chara was friends with an evil flower.
Then they kill the evil flower, ghost kid becomes not so chained to the inside of your head, Chara turns out to be a ridiculously powerful demon and kills Frisk.
And in this situation Frisk still doesn't know a single damn thing about Asriel, Flowey, or what their whole deal was with Chara. But this demon kid is demanding their soul in exchange for the world back so that's that I guess.
I'd love to see a fic where genocide Frisk and pacifist Frisk got a chance to talk and genocide just sits there slowly realising they convinced Chara to murder their brother who also happened to be the prince of monsters. Which also explains why Chara is the teeniest tiniest bit mad at Frisk if Frisk chooses to wimp out on destroying the world after Chara just killed their own strongest tie to it. Genocide Frisk would get their mind blown by all the lore they missed out on and pacifist Frisk would just be like sucks to suck. That's what you get for skipping out on dialogue you filthy stat maxxer.