Sharlan

 was a scientist of the planet Ashtallah. She, along with Brenna, was fascinated by all of the concepts brought to the planet with the arrival of the First Doctor, Susan Foreman, Barbara Wright and Ian Chesterton. Though not all to familiar with the idea, she believed herself to be in love with Brenna. She used a sample of Barbara's blood on other Ashtallahns as an experiment, in spite of it leading to them dying, wanting to increase their ambitions with the idea of a shorter life span after seeing the Doctor's TARDIS.

She didn't believe what she was doing was wrong, as she was unable to comprehend death. She and Brenna used genetic material from each other to create a child with the Doctor's help. When her child was in danger of dying itself, Sharlan got herself infected with the plague to protect it, succumbing to the illness herself. Brenna mourned her death. (AUDIO: The Invention of Death)