My brother did this too. he preferred spending time in his room writing and daydreaming about these made up places and stuff. He never forgot they were not real and stuff. It was just his way of sorting things out and having some queit time for himself. Later on when he was caught writing and daydreaming about this he-man vs the Hulk type place his teacher referred him to the school shrink for an evaluation. It turned out that he didn't really have a mental disorder by the standards of what was a mental disorder and what wasnt back in those days, he was just considered what they call a loner - person who would rather be left alone to do their own thing and used their imagination to do that. later on when he continued into adult hood to use this way of coping he was diagnosed as being Borderline Personality Disorder with anti social behavours.