Yet, weirdly are no-one's primary rival.
Forest and Derby have each other, Coventry historically see Villa as their main rivals. So, 3 derbys, but not the major focus of any of them.
Have you ever been in a dressing room? They may be in theory grown men, in practice they are single minded over grown adolescents with more money then sense and egos to match. Match that with various different little sub groups and cliques, all with the slightly different behavioural trends.
I stand by the comparison.