I was beginning to see that Phineas could get away with anything. I couldn't help envying him that a little, which was perfectly normal. There was no harm in envying even your best friend a little (2.20).
The more Gene justifies his feelings toward Phineas, the more we can see that he's still ashamed of his actions.
This time he wasn't going to get away with it. I could feel myself becoming unexpectedly excited at that (2.30).
This is a minor event – a small transgression at an afternoon tea – but it speaks volumes as to Gene's character. This is where we really start to see his resentment of Finny's seemingly easy success.
Was he trying to impress me or something? Not tell anybody? When he had broken a school record without a day of practice? I knew he was serious about it, so I didn't tell anybody. Perhaps for that reason his accomplishment took root in my mind and grew rapidly in the darkness where I was forced to hide it (3.62).
Notice the reason behind Gene's deepest envy of Phineas – it is not of his accomplishments, nor his skills or charm – just his goodness. Gene will realize this consciously in a bit – stay tuned.
In such a nonstop game he also had the natural advantage of a flow of energy which I never saw interrupted. I never saw him tired, never really winded, never overcharged and never restless. At dawn, all day long, and at midnight, Phineas always had a steady and formidable flow of usable energy (3.40).
Even after his accident, Phineas still possesses this energy – it's just no longer represented physically.
It was a courageous thing to say. Exposing a sincere emotion nakedly like that at the Devon school was the next thing to suicide. I should have told him then that he was my best friend also and rounded off what he had said. I started to; I nearly did. But something held me back. Perhaps I was stopped by that level of feeling, deeper than thought, which contains the truth (3.74).
Go back to that line at the beginning….
"You always win at sports." This "you" was collective. Everyone always won at sports. When you played a game you won, in the same way as when you sat down to a meal you ate it. It inevitably and naturally followed. Finny never permitted himself to realize that when you won they lost. That would have destroyed the perfect beauty which was sport. Nothing bad ever happened in sports; they were the absolute good (3.7).
Finny creates the Super Suicide Society as another form of sport, which ought to, according to his rules, be purely good. What Gene does by causing the accident is to turn the tree jump into a jealous perversion of that sport.
But examinations were at hand. I wasn't as ready for them as I wanted to be. The Suicide Society continued to meet every evening, and I continued to attend, because I didn't want Finny to understand me as I understood him (4.42).
This statement soon becomes ironic when we realize that Gene has got Finny completely wrong.
For a moment I was almost taken in by it. Then my eyes fell on the bound and cast white mass pointing at me, and as it was always to do, it brought me down out of Fanny's world of invention, down again as I had fallen after awakening that morning, down to reality, to the facts (8.98).
Earlier in the novel, we saw that Finny could charm his way out of any predicament, talk Gene into anything. But this ability, too, has been crippled by his fall.