Peri (mythology)

A peri was a kind of fairy in Persian mythology which started off evil before turning good. The temporarily deranged and recently regenerated Sixth Doctor took this as sufficient rationale to attempt to kill his companion, also named Peri. (DW: The Twin Dilemma)

Behind the scenes

 * Before strangling Peri, the Doctor quotes from the poem "Paradise and the Peri" by Thomas Moore.