Board Thread:General Discussion/@comment-32783587-20180302162510/@comment-28814491-20180303203843

Alpha Pitch 447 wrote: And the river person says: Beware of the man who speaks in hands. Now how would Flowey know about Gaster if he disappeared before Alphys did her experiment? 1) The assumption that Gaster is the man who speaks in hands. This is a theory, and should therefore be treated as a theory and not absolute fact.

Even with that assumption, however, there is still evidence to Flowey's knowledge of Gaster

2) Gaster may have been alive while Asriel was. There is no reason Gaster and Asriel would not interact, and it is very unlikely that these two famous people in a place as small as the underground wouldn't know of each other.

However, this doesn't explain how Flowey knows of Gaster's death, leading to the following.

3) Flowey could've learned about what happened to Gaster the same way the player does, FUN values. He has been RESETing for much longer than we have, and therefore could have experienced all possible FUN values. However, being an actual character and not someone playing a game, he would also have many more ways to gain information than we do. He might have simply asked someone what happened to Gaster, or looked through some historical record showing what happened.