Byron and Kenny are at constant odds and in constant competition with one another. We are forever hearing what Kenny does versus what Byron would do if the situation were reversed:
I could have done a lot of stuff to him. If it had been me with my lips stuck on something like this he'd have tortured me for a couple of days before he got help. Not me, though, I nearly broke my neck trying to get into the house to rescue Byron. (1.95)
It's clear that Kenny plays the role (mostly) of the "good boy" while Byron is the classic "bad boy." But of course, a close reader will see that these boys are not so perfectly black and white. They're also not total enemies, even though there are moments that might make us think so.
Before Birmingham, Kenny can see that something is going on with Byron, even if he doesn't understand it. Although Kenny sometimes really hates Byron, he's also hungry for those rare moments when Byron is friendly to him. And for all Byron's tough-guy-couldn't-care-less routine, he's the one who can see what's going on with Kenny after Birmingham—and it turns out he really does love Kenny after all.