The core readership for Percy Jackson is age 9-12.
I don’t know if you or your staff have had the chance to read farther than The Lightning Thief in the Percy Jackson series, but there are four other volumes.
The series is grounded on the premise that Percy must progress from age twelve to age sixteen, when according to a prophecy he must make a decision that saves or destroys the world.
I assume that XXXX would at least like to keep open the option of sequels assuming the first movie does well.