Sebastian Chiltern
From Tardis Wiki, the free Doctor Who reference
Dr Sebastian Chiltern was a 19th century physician. He was the twin brother of Nathaniel Chiltern.
He stole the temporal interferometry machine from Micah Scale, hoping to use it to cure his brother's insanity. Instead, it splintered Nathaniel temporally. One of the parts which remained in the 19th century locked Sebastian away in a sanatorium, since his claims about what had happened to his brother seemed lunacy. Constance Jane's Millie personality freed him to help her, but he abandoned her to help Nathaniel instead. He was killed by his brother for the way he had been treated. (PROSE: Camera Obscura)
