i think the one theory about how he wanted to impress lily is prolly the one that makes the most sense. james was prolly the popular kid who got everything he wanted cept lily. when dd decided to give him the head boy position he saw it as a way to straighten up and maybe get her attention. in a way james is like ron, i think just like ron no one really expected james to get it. ron was because he really wasnt all that popular, but james was because he was always up to no good and was kinda mean.