Oswald was the head of the Baskerville family 100 years ago. According to Lotti, Glen gave the impression that he liked being alone and was difficult to approach. Contrary to her beliefs, he was best friends with the loud Jack Vessalius and even told him about a secret passage so that he could sneak into the Baskerville house. Jack and Glen made a musical pocket watch together. Glen wrote the melody for it while Jack crafted it. The piece he wrote is called "Lacie."
One day he suddenly ordered his subordinates to kill everyone in the castle of Sabrié, the incident later known as the "Tragedy of Sabrié." He was killed by Jack but, according to Jack, Glen is still alive. He controls a chain called Jabberwock which looks like the jabberwocky from Through the Looking-Glass and four others being the Dodo, the Owl, the Griffon, and Raven.
Oswald became aware that Jack intended to drag all the people of Sablier into the Abyss, thus removing them from the Rule of 100 Cycles. Attempting to save them from such a fate, he ordered his subordinates to kill every person before that happens. He failed to stop Jack, and his severed body parts were used in the Sealing Stones.
