A former disciple under Cyrus, Simon was initially impressed with the palace's programs, feeling at peace there after going through a rough divorce and losing his job. As time went on, Simon became less and less interested with the religious aspects and saw opportunities to make a profit. Instead of fully-dedicated "spirital journeys" that would take months, Simon suggested that the palace should allow temporary relief - for a price, of course.
By 2076, Simon's tactics as the palace's business manager had become extremely successful. Simon realized that the guests needed very little to be entertained, and the once-struggling palace was suddenly netting thousands in profit. He came up with "enlightenment packages" that had hefty price tags, and even considered putting them on the market without Cyrus' approval, now that he had put him in charge of the palace's financial accounts. Simon went as far as spending money on "spiritual conduits" that pumped "spiritual incense" into the palace and made the guests high. Although he was unsure of what was actually in the gas, the guests were not appearing to be sick, so Simon continued to strike it rich until the Great War.
After the Great War, the palace continued to operate and interacted with the Diehards. However, the cultists' fate is unknown, as the residents of the palace all disappeared one night without a trace.
Simon Gladwell is mentioned only in Fallout 76.