Help me with my job!?

I'm currently working on subway restaurant and there's this guy who work 2 weeks after me and his an a$$hole. He always thinks the boss and telling what to do just because his aunt is the manager of that restaurant. Is that right for him to do that? He is not even the boss. I don't have any choice I have to get along with this people bec. I don't wanna lose my job. Is there any action that I can make to stop this guy? Would I lose my job if we have a confict?