Romance is the spark  that  ignites interest in this fantasy novel about spell seekers and curse casters by the husband and wife writing team of Cremer and Levithan. Each writer has individually authored popular Young Adult Fiction novels.   In Invisibility, they alternate each chapter between the voice of the invisible boy, Stephen, and the emotions and observations of his “ordinary” friend, Elizabeth,  the new girl in the next  apartment .  A lonely, awkward young woman from the mid-west, new to New York and happy to blend into anonymity of the big city of New York, Elizabeth is the only one who can see Stephen.   No surprises in the plot that the only person who can see the invisible boy may be the one who can break the curse put on him by a vengeful grandfather.  This is an easy read with the only memorable, serious note being the tender, insightful manner in which the sexual coming out  the younger brother is handled.  Recommended with limited enthusiasm.