If you think you've seen all the content that Baldur's Gate 3 has to offer, firstly, you'd be wrong – new lines of dialogue and instances are uncovered almost everyday. And, secondly, even the books within the game tell their own interesting stories. While a lot of them simply feature flavour text, some editions tell long-winded stories.
We're gonna be talking about this game for a decade and more.
For instance, the alchemy books in the games not only teach you about various recipes, but the writers have created them in a way that they have been extracted and published from the journals of master alchemist Haskinn Xhesilaphin. They tell of their venture into alchemy to help people, but things eventually take a morbid turn.
As pointed out by Sia on Reddit, the alchemy books start with Xhesilaphin's origins – a dragonborn who was descaled as a teenager. They dabbled in alchemy in order to bring back their hide. However, once that was rendered impossible, they continued to experiment and bring alchemy to the masses in the hope to improve their lives.
However, people being people, instead of using Xhesilaphin's work for good, people wanted to exploit their knowledge for poisons...