Thread: Basic Cat Question

I have 2 sister cats that are mostly Siamese. For years, they have been similar in nature. But a few weeks ago, one became very irritable and unfriendly. I have always feed them in their seperate bowls and they would jump on the table for food and act normally.
Then, a couple of weeks ago, one crouched and hissed as I filled the food boll and when I tried to pet her, she scratched me and ran from the table. Now, her sister comes in at night, sleeps on the foot of the bed but she won't let me get within a mile of her and runs when she sees me.
What could have caused this sudden difference?

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