In my sci-fi novel, there's one character that seems to stand out the most, an orphaned Devonian boy named Kenthew Rennald. Found by protagonist Captain Helen Chert when he was an infant on the streets, Kenthew was pretty much raised like a human child either on Helen's ship or in Helen's apartment back in Atlanta, Georgia. He recieved very little education because her superiors felt it'd be dangerous to let a Devonian boy in a classroom with human students. (Devonians are hot-blooded, aggressive, and have been known to pick fights as a way to deal with their problems.) When the story takes place, Kenthew is about seventeen, yet he acts and talks as if he's only nine. In the Devonian homeworld, a person of Kenthew's age should be a fully matured adult and serving in some kind of military role. Mentally, he's supposed to be twenty-five. He is none of that. He has the education of an nine-year-old and acts like one. So, I guess my question is: Would you say he was developmentally-challenged? If a human's education was cut off at nine years of age, what would be expected? Thoughts?