Two (The Abandoned)
From Tardis Wiki, the free Doctor Who reference
Two (The Abandoned) was one of Marianna's creations. The Fourth Doctor found him singing in the Cloisters. He started playing about in the TARDIS control room. He reminded the Doctor of someone from his youth. He was told by the Doctor to remove the weeds from the console. When Marianna arrived the Doctor realised that One reminded him of his imaginary friend Binker. (AUDIO: The Abandoned)
