Character Analysis
Ah yes, our esteemed narrator. There really isn't much to be said about him… besides exclaiming "Ah yes, our esteemed narrator."
This literary gentleman plays a pivotal—but in some ways absent—role. He's fond of taking baths. He's a good listener—he only pulls us out of the story at one point to question the hair color of Gustave's lady friends (which is a pretty perplexing detail).
In this sense, the Author is much like us, a conduit through which Mustafa's story can be told and retold, whether it's through the filming of a movie or the writing of a book. The Author's job, as he tells us in the beginning, is not one of creation but of replication. People "bring the characters and events to you," he tells us, "as long as you maintain your ability to look and to carefully listen."
However, he's certainly not devoid of all character. As he begins his story, he tells us of his reasons for visiting the Budapest—he was "suffering from a mild case of Scribe's Fever, a form of neurasthenia common among the intelligentsia of that time."
He's identified himself as belonging to the intelligentsia, then, and we know that he has a perhaps-psychosomatic disease. If you look up neurasthenia, you might come across a definition like: "an ill-defined medical condition with symptoms including general pain, headache, irritability, and emotional stress." Basically, the dude wants a vacation, and is willing to give himself a fictional fever in order to get one.
In the final credits we learn Grand Budapest was inspired by the writings of Stefan Zweig, an Austrian writer whose work was widely read during the 1920s and '30s. The Author is partially based on Zweig, although there may also be glimmers of Zweig in Gustave as well.