thought I'd provide an update for future reference. Prior to entering the stadium, my friend got pushed, his ears played around with, called all sorts of vulgar names from afar and up close to his face and given advice by police officers to be careful. Regarding the push, we were outside watching cars enter the stadium when out of nowhere, a drunken fan comes and pushes him. They exchange a few heated words and left it at that. Regarding his ears played around with, after we exited the subway, we were walking to the stadium and we pass a bar with a crowd of drunk people. They started chanting "puta madrid, etc..." and then a guy comes up to him and starts playing with his ears - we quickly walked past it.
Once in the stadium, we were surrounded by Barcelona fans but nobody really took it too far. At most a few dirty looks but that's about it. We were in the Category Premium 1 section.
We only saw about 3 other Real Madrid shirts. Met one teenager who was a Real Madrid fan but what was covered up. After the game, saw these 2 Real Madrid girls get hounded by some more Barcelona fans but they quickly walked on by.