"aggro". Sums it up - screaming, shouting, running towards, running away from, looking for a fight but rarely getting into one. If there was any actual fighting it usually came about by accident when one poor sod got isolated and ended up having his head kick in as he lay on the floor. The other 95% of fans looked on in the same way you would if you saw two groups of baboons trying to mark out their territory - curious, but detached.
The childish mentality extended to the attempts to make it all sound so cool - naming this group, this 'firm', the boys from such and such place, respect for that firm but not another. Unfortunately it meant we all had to watch football through ugly large chainlink fencing for over 20 years, though it probably didn't bother those involved in the 'aggro'.