Character Analysis
As the Murrys' pet dog, Fortinbras's main role is to run around and bark at things. But his bark has a bite: it's his uneasiness that clues the Murrys in that they're about to get a visit from Mrs. Whatsit, and Charles Wallace cites his lack of growling at Mrs. Who as evidence that the strange old woman can be trusted. (Fort does growl at Calvin O'Keefe, though, so the dog isn't an infallible trust-o-meter.) Fortinbras's unusual name comes from Hamlet – Fortinbras is the name of the prince that comes in at the end after everyone dies – which tells us something about the Murrys as well: they're the kind of people who would name their dog after a semi-obscure Shakespeare character. (For more on Shakespeare in A Wrinkle in Time, see "Symbolism, Imagery, Allegory.")