My 3 year old son David has an imaginary friend called Bobby. He talks and plays with this "friend" and seems to live in an imaginary world. Is he going to become obsessive or psychotic?
Young children (two to three year old) create a lot of these friends (real persons, figures of comics or TV or pets) and interact in a special way. Daydreaming or imaginary world can help them to overcome sad feelings or times when they feel lonely. While the kids usually know that this imagination is not real it might be difficult to separate true world experiences and stories of their rich imaginations. So your child might tell you wonderful fairy tales at this age. There is no need to worry about it. These kids will not become psychotic or obsessive later in life.
But you should be aware of the rare possibility that ongoing trauma of children can be a reason why children stick to this imaginary world longer than normal. It is a possibility to find a "secure place" and to escape from emotional or sexual abuse.