Anna Alter has created a wonderful read with Disappearing Desmond. The cover does not give the story justice, as it is hard to tell who/what Desmond is and why he would be hiding (which is sort of the point).
Desmond usually disappears into the background at school, play, and recess. No one notices or invites him to play. Eventually, the new girl Gloria notices Desmond and invites him to play. From that day on, Desmond can't remember why he ever wanted to hide.
Soon, Desmond begins noticing other students that are hiding and becomes a friend to them.