Complex sentence: He is portrayed as an 11 year-old child most of the story, until he abducts Jane Jerome and it is revealed that Mickey committed those crimes 30 years ago, and was planning to kill Jane for dating Buddy.
Split into simpler sentences: He is portrayed as 11 most of the story, until he abducts Jane Jerome. It is then revealed that Mickey committed those crimes 30 years ago and is planning to kill Jane for dating Buddy.