Essentially, Misha has no stable identity. Who or what he is at any given moment is largely defined by other people. So for instance, when the story begins, he thinks he's called "Stopthief" because that's what everyone shouts at him. Later on he's given the name Misha Pilsudski, but he still doesn't quite know who he is.

At various points in the story Misha adopts the persona of a gypsy, a Jew, and a member of the Milgrom family but without actually being any one of them. It is this lack of a fixed, stable identity that sets Misha apart from the other characters in the story. Crucially, it's also what helps him to survive for so long. To a considerable extent, World War II, especially as it was fought in Poland, was a conflict in which racial identities were considered essential. Having the "wrong" racial identity could mean death. But because Misha has no such fixed identity, no sense of where he truly belongs, he's able to avoid the fate of so many others at least for a time.

There are many ways to describe Misha in Spinelli's Milkweed. How we describe him depends on where we are in the story. We can describe him as an orphan boy growing up in Warsaw, Poland in the 1930s who has no name except "Stopthief" until he is given an identity. Further, we can describe him as an innocent who never truly understands the horrors of the Holocaust going on around him. After Misha meets Uri, we can describe Misha as a boy happy with his new "Misha" identity and who is finally a part of a group: a collection of vagrant boys hiding in a stable with the leader named Uri. After Misha meets and befriends Janina, we can describe Misha as a boy who now has a Jewish friend and, further, that the friendship means so much to Misha that he travels with her and her family into the Warsaw ghetto. Near the end of the novel, after Misha's interaction with Wendy, we can describe him as a grandfather of a young girl who gives him a new identity: "Poppynoodle." Because this is the first actual family member bestowing a name upon Misha, we can say this is finally where he receives his real identity.