after the overnight trip to the beach, what does Gene decide finny is trying to do to him? what leads gene to this conclusion? how does gene feel when he realizes hes wrong?

Gene believes that Finny is trying to keep him from excelling, and that Finny is engaged in some sort of competition with him, are as far from the truth as they possibly can be. Gene's misgivings about Finny taint his usually keen perceptions of what Finny means, and Gene's jealousy of Finny helps him to create an utterly unflattering portrait of Finny to believe in. Gene misconstrues Finny's remark about Gene wanting to be head boy at the school as meaning that Finny does not want him to achieve; Finny is really just conveying his disregard for school hierarchy and position.

Gene also abandons his usually right-on interpretations of Finny's tones of voice; when Finny tells Gene, in a mocking tone, that Finny would be jealous if Gene was first in his class, Gene disregards everything he knows about Finny's sarcasm and takes the comment completely seriously. Gene's jealousy and ill-will lead him to see in Finny whatever traits he wants to find; his characterization of Finny is strongly determined by his own feelings, and can be incorrect because of this emotional influence.

Gene's "realization" of Finny's allegedly competitive behavior "broke as coldly and as bleakly as dawn at the beach" (44); the simile repeats the imagery at the beginning of the chapter, suggesting daybreak as a motif and metaphor suitable to describe many aspects of the story. Gene's language and tone become increasingly more dramatic, perhaps even melodramatic, as he describes the influence that this false realization had on him at the time. He says he was "despairingly in search of something" to cling to, blowing his mental separation from Finny up into something life-shattering, in a way (45). Yet, these words definitely seem added in retrospect; Gene says he does not act differently than normal in the face of this dramatic "deadly rivalry," gets on well with Finny, and devoted himself to his studies (46). Gene's social life remains much the same, as does his outward manner; he does not act as destroyed as he claims to be, but rather he is very much intact, but vengeful. Gene finds the "truth" that he alluded to at the end of Chapter 3, but it is not a truth at all‹it is a dangerous falsehood‹and in this confusion, he also misrepresents his destructive anger as genuine despair.

In Chapter 4, a dark side to Gene's character is finally revealed, and allowed to work its mischief. In this section of the book, especially with the revelation that Gene is completely wrong about Finny's alleged sabotage of his grades, Gene and Finny become even more diametrically opposed; Finny seems more pure and good-hearted than before, while Gene moves into the gray area that he saw on the beach, and that he thought Finny to inhabit. Gene, unlike Finny, has a nature that is corruptible through envy and suspicion; and, once inflamed, the bad side of Gene's nature takes him over, and causes him to harm his friend in a terrible way. The end of the chapter, with Gene causing Finny to fall from the tree, casts them almost as good vs. evil; Finny is cleansed of blame and shown to be pure of heart in this chapter, while Gene's character is revealed as being more pernicious than previously imagined.