Viola's brother was a character in William Shakespeare's play Twelfth Night.

While outlining the play in a meeting with Richard Burbage and the Fifth Doctor, Shakespeare said he had a mind to write of "a woman who was shipwrecked" who, "fearing her brother [was] lost at sea and anxious for her own safety, doth counterfeit her own brother in character and apparel". The Doctor determined this plot to be "rather complicated" and not "make much sense", questioning who would mistake a woman dressed as a man for the real thing. Burbage elaborated that she would be played by a boy. He still wasn't convinced and in an attempt to prove his argument suggested what would happen if Viola's brother turned up, asking if it would be confusing for both the characters and the audience "if someone [met] the brother and [thought] it's the boy being a girl who's pretending to be the brother but [was] actually the sister". Burbage loved this idea and exclaimed that this hypothetical scenario had to be included. (PROSE: Diary Extract)

Behind the scenes[]

Although not named in Diary Extract, the character is a clear reference to Sebastian.