The Rani, so far played by Kate O’Mara, is a time lady, sort of like the Master. She is more scientific, and has a very scientific mind without any thought to consequences or ethical scientific behavior.
They were supposed to have gone to University together, she said about the Rani and the Doctor.
She says she would like to have worked with William Hartnell or even the now Peter Capaldi. (although she did love working with McCoy).
Questions from the TARDIS tin, The Rani, answers your questions.