the way i understand it there are no absolute's in any curva in Italy - except for mayby really small teams who are dominated by one group e.g Varese (Blood/honor) - but even then, there are fights to control the curva ext.. You will find all kinds of fans with different political beliefs in all the major Curvas in Italy.
for Inter there are 5 major Ultras groups
BOYS SAN - the oldest and most powerful group - historically very right wing, less so today given government repression ext..
ULTRAS - more A-political, but still on the right i.e nationalist/fascist
VIKING - probably hard right fascist - links with blood and honor ext..
IRRIDUCIBILI - hard right - former name - skins - not uncommon to see skinheads, nazis ext...
BRIANZA ALCOOLICA - the only real A-political ultra group. but not very powerful in the curva.
there are a whole host of smaller groups who are either attached to the 5 big ones, or constitute ultra groups of their own. most are right wing also, but you should note carefully that Nazis and skinheads are a distinct minority. many people might sympathies with these groups, wave Celtic crosses ext.. but they are not Nazis themselves - they are mainly nationalists and old-school Italian fascists. one of the bigger of the smaller groups is milano nerazzurra who are a very old historic groups and i would say even have left-wing roots.
ultras today in Italy is a dying tradition with all the government repression and ultras groups selling out for $$. if you want to see true ultra mentality forget about the big teams and groups in the Serie A, look back at some of the smaller teams in Italy playing Serie B,C ext..