Everyone remembers and doesn’t remember Gaster at the same time. Like, if they see something he built they usually will know it was built by the old royal scientist, but they wont know that he was the royal scientist. And if you bring him up in conversation, their memory will be jogged and they will be able to tell you about things they remember about him if you work hard enough at it. But as soon as you even slightly change the conversation, they forget everything and you have to start the talk all over again. Its really annoying.



Whether or not people can see him existing right NOW though? It really depends.

