From the in-game encyclopaedia
A relative of Esther, Sean Ambrose is a recluse, wholly dedicated to his research and work. He never married or had any children, and science is the only love he has ever known. A skilled time traveller, but eager to experiment and try to push the boundaries of the craft, he is considered to be a visionary by some, but a madman by others. He takes care of the wounded Esther after she is saved by Miss Charlotte, and arranges it so that the baby Esther is brought up at the orphanage.