"I am universally referred to as the Master, Lord of Time. And there are only two things I require from you. Your submission and obedience to my will!"
—The Master
The Master, also known by various other aliases, was a renegade Time Lord, originally a friend and long-time opponent of the Doctor.

At a late period in his life, the Master came to adopt a temporary identity, calling himself Linfred, and infiltrated the wizard society of medieval Scotland, while claiming to be from southern region of England. His true plans unknown, the Master eventually married a human woman and had seven children with her, leading to him becoming the apical ancestor and founder of the Potter family.

He was betrayed by them, and his essence locked away within a Chameleon Arch, which was then entombed inside a subterranean chamber. Only hundreds of years later would he be freed, when the pocket watch was found by one of his descendants, who had no idea of the fob watch's real purpose, opening it and releasing the Master's essence.