One of the things in this discussion of Fredo is the difference between behavior and motivation. Fredo did start out as a nice, meek boy who was thrown into the middle of a highly energetic family, to use a term. He's this nice little guy absolutley in awe of his father. He's got one brother who's really agressive and physical and another one who has his father's intelligence. He reaches an age where he realizes this comparison (like we all do), sees his brothers operating in the family business, and gets thrown into the business himself in a foreign environment (Vegas) and exposed to another quite strong personality (whose qualities he can't come anywhere near matching). In each case, Fredo emulates behaviors that he sees other strong or cool or respected people exhibit and which he thinks will please those around him. He's in over his head. In the end those behaviors don't bring him the kind of reinforcement that he seeks. As a result, he becomes frustrated. Frustration leads to anger and rash decisions, stupid decisions. I don't think he's complex at all. He's not smart enough to realize that respect is earned, that power is accumulated, and that thoughtful productive behavior is essential to respect and power.