FelineFriends 
If you own two or more cats, chances are you've seen them turn into hissing, snarling adversaries atleast a time or two. What causes feline housemates to turn into occasion enemies?
Sometimes the fighting that occurs when cats are introduced together suddenly can be so severe as to lead to long-lasting grudges and the building up of territoriality within the house.  Cats need a period of time to adjust to each other, to figure out who's up and who's down and to work out their time sharing. Sometimes cat fights are the result of redirected aggression. You may have two cats who are normally buddies.  And then suddenly one of the cats bccomes highly aroused--by a sudden noise or the sight of an intruder cat through a window--then it discharges its aggression onto a feline housemate, who has no idea why it's being attacked.
Although there are many reasons why they may fight, given time, most cats can learn to live peacefully together.  However, that does not necessarily mean your cats will become best buddies.  Keep in mind that every cat has its own unique personality, and sometimes their personalities are going to clash.  It's up to you to help your cats live together in harmony. Here are some suggestions:
 
 
Start with a good introduction......When you first bring home a new cat, you should
introduce it to your resident cats slowly and gradually.  Put the new cat in a room by itself, shut the door, and let your resident cat have the run of the house. Allow the cats to smell each other under the door. After a day or two give them limited contact through a screen door or crack the door an inch. Give your cats a chance to smell each other and get used to the idea that there's another cat in the house before they actually have to meet face to face.
Associate positive things with the new cat in the resident cat's mind.  Bring the new cat out when you do your grooming or petting, are playing with cat toys, or are handing out treats.  Cats learn by association, and soon they will associate being together with wonderful happenings.  Rather then seeing the new cat as an intruder, your resident cat will begin to see the new cat as a catalyst for an enjoyable time.
Create safe hiding places.  Provide a variety of nooks, high perches, window ledges and other desirable "hangouts" throughtout your home, so your cats don't have to fight over a couple of prime spots, and so they can have places of refuge if they want to get away from each other.
Cue into your cats' body language. Know when a cat's body language says it's ready to fight.  Then be prepared to curtail the fighting before any fur starts flying.
Redirect their behavior. If you think one of your cats is about to start a fight, redirect its attention to something more attractive. Get out a toy on a string, suspending it above the cat. "Oh, forget that other cat, I found something fun to chase." This way, you keep the victim cat safe, but you do it in a positive way.
Don't overreact.  You may see one cat smack the other and begin to panic. Try to stay calm; don't interfere too fast. If you jump in right away, your cats may think the situation is worse than it really is. They will pick up on your emotions, and when you are tense, the cats will be also. Realize that even if your cats are best friends, they're bound to get on each other's nerves now and then.  The key is to know each of your cats' individual personalities, so that you can tell the difference between a minor disagreement and a serious fight.