My cat keeps attacking my brother lollll?

i have my 15 yr old brother over for the spring break. he came last yr n my cat kept hissin at him like crazy. well ri now he is hissing at him. but the thing is that if a cat doesnt like some one they arent going to start playing with them right? lol well cukoo hisses and growls at my brother but as soon as my brother walks away cukoo runs after his feet and smacks them n then runs back to his house and occasionally he'll play with my brother so idk if my caT IS confused or what loll but its jus funny to see them. if my brother is sittin down or somethin the cat will come by him n sit with him or got lay by his bed.