He was rather evil and twisted for his family, but was Satthralope's favourite and he showed strong hatred towards the Doctor. His behaviour was largely disapproved by his cousin Innocet. When he was young and when the Doctor was disowned and cast out, working at a lowly position in the Capitol, Glospin came to gloat over his replacement by Owis. He claimed to have found genetic anomalies in the Loom records which proved that the Doctor did not belong to the House of Lungbarrow and he presented this proof to the Prydonian Chapterhouse. Were this upheld, the Doctor would be executed as a Loom-jumper and Glospin would secure his birthright. The Doctor furiously attacked Glospin and as they fought, the Hand of Omega appeared and drove Glospin off, leaving a scar not even his later regeneration could heal.
The inconclusive fight allowed Glospin to take a genetic sample from the Doctor, returning to Lungbarrow and using the sample to 'force' his next regeneration into the exact double of the First Doctor, allowing him to murder Quences before regenerating again in order to frame the Doctor for his murder, so that he could subvert Quences' will and become his successor as Kithriarch instead of the Doctor. This led to the House of Lungbarrow being buried and forgotten for 673 years, leaving Glospin trapped with his family as the House turned against them, certain rooms making the psychically sensitive Cousins relive the events of the original collapse while Glospin spent most of his time with Owis, nurturing Owis's resentment of how others regarded him as an inferior substitute for the Doctor.
When the Seventh Doctor returned to Lungbarrow he found Glospin locked in the stove as punishment for stealing more than his ration of fungus, and there was a moment of instant mutual recognition and hatred between them, probably because of what had occurred in the past. Glospin proclaimed that the Doctor had finally returned to gloat over the situation he left his family in. The Doctor was then accused of murdering Quences and Arkhew- actually killed by Owis on Quences's 'recommendation' to ensure that he couldn't identify Glospin as Quences' true killer- but his investigation allowed him to reveal Glospin's role in the crimes. When the Doctor rejected his inheritance and the furious house struck out at him, Glospin attacked the Doctor, who had ruined his family, with Satthralope's key, but Quences- his 'ghost' inhabiting the body of Badger- killed Glospin. Lungbarrow toppled over the cliff with Glospin's body still inside, ensuring his permanent death. (PROSE: Lungbarrow)