Narrator (The Room with All the Doors)

A person spent years trapped in the Multivarium with the Second Doctor, without getting hungry or tired. They couldn't remember how they got there, but they could remember ice cream at the seaside. (PROSE: The Room with All the Doors)

Behind the scenes
The narrator of the short story is never named. In fact, almost no information is given at all, including their gender or even species.