Well my two new cats I got this week are fighting each other. My 2 year old cat Sarah keeps hurting my 2 month old kitten snowy. When they cross paths they hiss and scratch each other, I don't know what's up with them. Please reply!
Are they both new to you and the house? Or is even one new? This is normal behavior. It can take a month or longer for them to get comfortable and accept eachother... Not always but sometimes that long. I would separate them. The 2 month old is too young and the older one could unintentionally hurt her. Usually females will not harm a kitten... But she could unintentionally.
Just keep them separated for a couple of days at least. Then you can try a positive reinforcement introduction where you offer them something yummy... Praise them for every good interaction aka no hissing, growling or slapping. Do not punish. Just separate them if it starts to turn ugly. Soon they will associate noms and good things with eachother.
The biggest thing is not to get discouraged... It can and often does take time. Mine average about 2 weeks. But each cat and situation is different.