If there was ever a co-dependent relationship, it had to be Gene and Finny--at least, from Gene's side. Gene's friendship with Finny is tainted by envy; while Gene does well in school, Finny is the more gifted athlete, and as in athletics, life excluding academics, seems to come very naturally to Finny. Finny is carefree, happy-go-lucky, able to talk his way out of most any sort of trouble--and what Gene absolutely cannot tolerate is when he figures out that Finny does not feel a reciprocal jealousy of his (Gene's) hard work and academic success. So, like in any co-dependent relationship, Gene's "friendship" with Finny is not really a friendship as much as an unhealthy emotional attachment to what Finny represents. As much as Gene feels resentment and irritation toward Finny, the idea of not being part of Finny's carefree, jovial, amiable life is more intolerant to him. When Gene jiggles the tree and causes Finny's accident, the need to be part of the fun has been trumped by the malevolent feelings Gene carries toward his "friend".