Thanks Flavia. Good read. Out of all places, LOL also had a pretty good article explaining the rivalry.
Sounds like the rivalry initially originated in the different identity the two clubs represented, Barca being the flag bearer of the Catalan identity and its independence movement while Espanyol was the club of the royalists and the Spanish speakers in the city. But later on Espanyol's fanbase had also expanded to the Catalan-minded people in the city, apparently. So I really don't understand why and how some Espanyol fans, being Catalan themselves, could encompass so much hatred toward us.
I come from a city where there is only one team in the tier A league in the country, so growing up I couldn't fathom how heated a derby could come into being. Different parts of the same city? Different social-economic class represented? Different ideologies represented? Understandable. What I don't understand is "tradition", ie. " I am supporting XXXX because my father/family supports it". Certainly family preference plays a role when the kid is growing up, but I always thought as an adult one should make his own judgement by looking at a slew of factors, such as the style of a team's play, the players a team has, their results, what a team represents etc. and makes his/her own decision.
I guess I will never understand how some Catalan-speaking Barcelona residents could hate us so much.