There are many reasons why cats do not like certain people, as cats often do not even like to associate with their own kind. It might be because your kitty doesn't like the way your friends smell, doesn't like the way they interact with the cat, or it's just a simple case of 'I don't like you. Leave me alone.' Most of the time cats will warm up to anyone, so just give them a little bit of time, and do not rush things. The cat probably didn't like you when it first met you! I hope this helps! Cats are very interesting.