Character Analysis
Freud had a number of brothers and half-brothers, some of whom lived long and fruitful lives and one of whom—his brother Julius—died in infancy (source). Throughout The Interpretation of Dreams, Freud often refers to the presence of one or another of his brothers in his dreams; but since he rarely identifies which brother he's talking about, none of them appear as three-dimensional, individual characters in the book.
In Sigmund Freud's Dreams, Alexander Grinstein offers an intriguing account of the unconscious presence of little Julius Freud in Sigmund's dreams. According to Grinstein, a number of Freud's dreams—including the Non Vixit Dream—express Freud's unconscious pleasure (and guilt) for having survived the little child who died in infancy (source). Since Freud doesn't really address this himself, Grinstein and others have had to do it for him.
Although Freud doesn't present very detailed analyses of the significance of his brothers in his dreams, there's lots to discover for those who are brave enough to do some psychoanalytic sleuthing.