Sudden Aggression Toward Inanimate Objects

I have two female rescues that I adopted about 2 years ago. One is a needy, large 2 year old and the other a very petite, ginger, "junkyard cat" about 3 years old. I have never had issues with aggression in either cat - aside from an old roommate's new puppy and play/dominance fighting with each other. A few days ago, I started noticing that my smaller cat was acting a bit off. My brothers moved back from college and they leave their laptops in my living room. It should be noted that my brothers come home often and this is not out of the ordinary - both cats adore my brothers as well. However, the 3 year old is suddenly obsessed with attacking any and all mousepads in her vicinity. Likewise, spare socks that have managed their way out of the hamper are a new enemy. She will bat them, hiss at them, bite them, etc. When I try to pick any of these things up and show her that they aren't dangerous, she cowers in fear. Just last night I saw her hissing and batting at the couch cushion. She does not appear to be sick, but does have diagnoses for PICA and feline herpes. Her PICA is usually a plastic/paper problem, never rubber or fabrics. My other cat seems to be completely fine and will look at the 3 year old as if she's thinking "What the heck is she doing??".

Any clues or tips would be greatly appreciated!

Also, the aggression is never directed at myself or anyone else.

Cats can develop weird habits, and some do hiss at things for play. You can find posts with examples of this on the internet. Something to keep an eye on but probably nothing. If your concerned, it seems like more than a new play habit to you, than a vet visit is in order.

Things smell differently to her - it sounds like all the stuff she is attacking and hissing at are related to your brothers' homecoming? Maybe different smells on these items than before, or she is merely reacting more this time than before? Even the couch cushion could somehow be related to some strange smells your brothers brought back on either their clothes and/or belongings? This would all be more applicable if they haven't been home too long, and if so should dissipate the longer they are there.

Look for other signs of possible illness over the course of coming days/weeks - and, a diminished reaction to these objects. Don't bother to try to show her they are harmless - rather redirect her attention to something she likes - a toy or a treat.

Have your brothers been hanging out with another cat, a dog, a new roommate?