kitty attacks cat

hey everyone!! i'm' back. i'm brad pitt jr's momma. he's about 8-9 weeks now and doing wonderful! the only problem i've had started today. my friend is in the middle of a move and needed to know if i could take care of her cat for a few days. he's about 2 years old now and really really sweet. i said of course, thinking my kitty would like him =) well....they bring over the cat...and my kitty hisses at him! it was the first time i've heard my cat hiss! so i was like..oh no...the cat is 13lbs. and my kitty is the tiniest thing so we think it's cause it's afraid of him...but everytime it sees him it wants to attack!! it hisses and makes weird noises and tries to scratch him. my friend's cat just ignores it and doesn't mind, and my friend said that her cat won't scratch back cause her other cats always scratch each other and fred (her cat) never scratches back. i believe her, i just dno't want my kitty hurting him. i put my kitty in my bathroom (it's pretty big, big enough to have him run around and stuff) i put his scratching thing in there with his fav toys and he hasn't complained. bu ti'm letting the other cat roam around the apartment cause my friend said it meows loudly when its bored. whaht iwant to do is try to get my cat to not be afraid of my friend's cat...any tips?

You need to introduce strange cats to each other slowly and gradually. Chucking them in a room together will cause them to hiss and growl at each other (as you've seen). Check out the stickies at the top of the page

It is never wise to put two cats together right away. It upsets the balance of the home and makes both cats go on edge and fights (and worse occur). Because the other cat is visiting, that cat should be isolated in a room with a baby gate stretched up the doorway veritcally. Let the kitten have his home, and the other cat stays safely in the room with food, water, toys and litter pans. You can feed them close to each other so they get used to each other, one on each side of the barrier, but don't penalize your kitten for being Alpha and wanting to protect what is rightfully his-