In appearance Chappie is a child like many others. He has a normal childhood, with his joys and his problems, and as with everyone, his environment makes his character forged in one way or another.
Little by little Chappie grows and becomes a man, but there is something about him that makes him different from the others. Despite his appearance, Chappie is actually a robot, the first robot in the world that has feelings and thinks like a human.
That is going to bring many problems, because when you discover very powerful forces are going to go after him with the idea of eliminating it, because there are those who do not tolerate that the robots are like humans, because they think they can be dangerous.
What will happen in the end with Chappie? If his pursuers find him it is possible that they eliminate him, being then he the only robot that felt like a human.