I have a 5 year old cat, Callie, who is VERY agressive towards other people. She is lovable when with me but the minute someone else is here she loses it. She hisses, screeches, spits, and bites. Since I have had her it has just been her and I living here. When my mom visits Callie will attack or won't let her up/down stairs. She is awful at the vet..so bad in fact that he gave me tranqilizers to give to her before we go and it is still awful. My boyfriend is here alot on the weekends and sometimes she is ok with him and other times she will attack him for no reason. Can someone help? I don't know what to do.