Ted Peterson worked as a designer for Arena, lead designer for Daggerfall, and writer for Morrowind. Many of the in-game books you'll find in the second Elder Scrolls were penned by Peterson, but he hasn't been at Bethesda in quite some time. However, he's returning to this world in a fan-made remake of Daggerfall to lend a hand with new books.
"One of the most wonderful interactions I've had is with Ted Peterson," Daggerfall Unity creator Gavin Clayton said. "Ted has sent me kind words and seems to enjoy watching his game come to life all over again. For those who don't know, he's behind a lot of the lore and the world inside The Elder Scrolls.
"Ted has started writing a series of in-game books for Daggerfall Unity, intended to be available in the world only after the main quest is complete. These books explore the motivations and backstory of Lord Woodborne, the antagonist in Daggerfall who murders King Lysandus and sets the main story in motion. Ted is writing these books and releasing them to our community one at a time for feedback. Once he’s finished and ready, they will be introduced into the game."
The aim of these new books is to "fill in some gaps in the main story quest" without changing the game itself - these are intended to add more context and information to the world of Daggerfall, the game that arguably sparked modern Elder Scrolls as we know it, introducing the likes of dragons, the Dark Brotherhood, and even Khajiiti tails.
One of these books aims to address the mystery of Lysandus and Numidium which Peterson said was not "explained clearly or at all." However, he did clarify that what he writes is not "official canon" because he is not working for Bethesda and Daggerfall Unity is not affiliated with it.