What makes Whiskers so mean?

Whiskers is the black and white cat. She is an 11 year old female.

Whiskers has been our only cat since she was a kitten, and she has always had a bad attitude. She only wants to be petted when she decides it is ok. You can pet her and she will bite you or scratch you if you don't do it the way she wants you to. She is also unfriendly to strangers. Very unfriendly.  Particularly feline strangers.

The younger yellow and white cat is also a female. She is new to the house and seems to be trying to get to know Whiskers. We haven't decided on a name for the brown and white cat yet so for now we call her Kitty. Kitty is about 9 months old. Kitty is very sweet and likes to be petted.  We think this is probably why Whiskers hates her.