Around four years ago I adopted two rescue kittens that bonded as siblings. I moved out of my parents house almost two years ago, and this year my parents decided to adopt another cat. I brought my cats over for Christmas break, anticipating that the introduction process would be tough with my parents two cats. The plan was to have my cats in the basement (it’s bigger than my apartment and used to be their favourite place to hang out when we lived here) and my parents cat could roam freely on the other floors as we slowly introduced them. Almost immediately after a very brief introduction through my cats crate as I was unpacking the car, the cats began hissing at my parents kitten so I brought them downstairs. However, at this point my cats aren’t even able to be around each other. One of them is clearly the antagonist, hissing and swatting and launching at my other cat and me as well. She is the sweetest little cat, and has never bit me a day in her life, and now all of a sudden she’s hissing at me, my mom, attacking our dogs when they go near (she used to love the dogs) and really just is not acting like herself. It’s only the first day, but I’m really worried I traumatized her and I don’t know what to do. Here they are just moments before disaster