I think rivalries are based on history and what happens between them during actual played games. For instance, a heartbreaking loss or repeated poor sportsmanship. However, I also think rivalries can be personal, as my name states. I live in Denver, so being out here, I hated CU and their fans. Just because they may not be NU's rival...they were indeed my rival. I think that's why many NU fans think of IA as such. Actually, I may just change my name to IA Sucks...