weird cat behavior: help!
My adult male cat had to spend last night at the vet's office. I just brought him home, and our one year old female reacted really badly to him. She won't stop hissing and growling at him. Normally their relationship is very much big brother being pestered by his little sister. She follows his every move and he humors her up to a point. Then they tussle good naturedly for a bit and take a nap. They're not best buds but they more or less peacefully coexist.
I've never seen her good truly aggessive with him before. I assume it will pass, but it's sort of just weird and upsetting. I've always had multiple cats and never seen one react that way when the other has been away at the vet. Do anybody else's cats react this way to one another?