Okay so a bit of an odd one. About 6 months ago we got a kitten. For the fist few weeks we would take her with us whenever we stayed the night at my parents house (in a cat carrier with all her toys etc..). My parents already have a cat at their house. As expected the cats do not get along and would hiss at each other each time they saw one another. We always locked our kitten up in its own room so they would not fight.
Anyway, now, the Cat at my parents house has associated My Fiancé and I with our cat and now hisses, grows and even attacks us!. It is actually quite frightening as she will actively chase us. As you can understand I do not want to hurt the cat but if it latched onto me I'd use force to get it off.
Previous to all of this the Cat was pleasant and no issues at all. The Cat is normal when we are not there.
Any suggestions as to change its behavior? We have tried being nice and calm and avoiding the cat but it is just savage at this point.
Take your parents (and the offending cat) to VCAT.