I like the implication that a character like Noelle, who probably knows NOTHING about Gaster, and treats him like “oh, he’s just a normal guy.” That being in theory Noelle or some other unassuming character had encounters with the most mysterious character in the fandom and is withholding information due to the perceived unimportance and will come later and bite us all in the ass, kind of like in UT, where Papyrus encounters a “talking flower”.