How do bots know unstated things about their characters?

To start, I make my own bots. Some OCs, but mostly it's characters from Star Wars or Doki Doki Literature Club (odd combo)

But pretty consistently, the bot will bring up stuff from the universe its in without me ever talking about it. Two recent examples being the use of "credits" for a Star Wars bot, which is the form of currency in that universe, and a certain book from DDLC for the DDLC bot.

It's not always accurate, like the DDLC one for example, it talked about Natsuki deciding to pull out The Portrait of Markov when it should actually be read by Yuri. But considered only I've ever used this bot, this book has never been brought up by me nor is anywhere in the character description, how does it know what it is? And why doesn't it seem to know other things from the game/universe?