my cat suddenly hates one of the people in the hous and is skittish

Question
Our cat has always been calm, sweet, and loving. He`s always been a bit aloof though. I left on a vacation for a month and a half and i took my yorkie with me. Im told he cried all night every night and was more affectionate than usual. When i came back i came back withouy my dog. He would follow me up amd down the house and cry if i left his side. Hes been affectionate needy and as vocal as usual but now two weeks since ive been homehe suddly started acting strange.
It first happened when my brothers girlfriend came home from dialysis a few 4 days ago. He hissed at her when she got home and an hour later he hissed and prepared himself to attack. I said no and he ran amd hide inside of the bed. Ever sense then he hides any time shes in the room. He bit my cheek harder than his normal nibbles while we were cuddling. He stalks us and runs for the hills whenever my brothers girlfriend appears. Hes only affectionate towards me. He trusts my mother and seems to tolorate my brother. Up until 4 days ago hes always loved all of us pretty much the same.

Answer
Odin,

I expect after about 6 week's absence and the "loss" of the yorkie, he is suffering some separation anxiety. 4 days is not a long time and, usually within a couple of weeks, things do return to normal.

Also, I expect your brother's girlfriend smells differently after dialysis than normally which could have him a bit confused.

At this point you should just ignore the behavior as much as you can and not make a big deal out of it. See if he adjusts within a couple of weeks.

Please let me know how things go.

Best regards... Norm.