Darby was an adviser to King Leck of Monsea and later to his daughter Queen Bitterblue. After his joined betrayal to Bitterblue with Thiel, Rood, and Runnemood, he and Rood were sent to prison. By the next day, Darby had hanged himself in his prison cell.
Prior to his suicide, Darby had also co-authored a series of medical pamphlets, which later disappeared (presumably taken to hide the advisors' past).
Backround
He had trained as a healer along with Thiel, Runnemood, and Rood, and was considered very successful. Because of his skills, he was used by Leck to help torture his victims.
Darby had one yellow eye and one green eye and was graced with never sleeping.