Flowers for Charlie

I think this song is basically about what it says it's about, all be it with a bit of an extended metaphor. Charlie, as some have pointed is a general army term for the enemy, and the song is indeed about a war. As many have also pointed out Charlie was also Elliott's step father and they were locked in a war of popularity, perhaps competing for his mother's affections. It's not entirely unheard of for there to be jealousy between step parents and biological children and vice versa. What Elliott is saying is that he doesn't want to fight this popularity war, but he's not trying to win Charlie over either, he's not trying to make friends. He simply doesn't want to worry about this issue, because staying alive gives him enough to worry about. He ends the song by basically telling Charlie not to tip toe around him because the war is over, it's a free world and he can do what he wants. So it's not so much about forgiving Charlie as it is about giving up on a sort of active resentment and animosity.