Trevor didn't get far into the monster hunting world without being hyper observant.

As the cat approaches, he frowns, sniffing the air. Magic usually leaves a mark or a scent, and he just caught a whiff of something familiar. It takes him a second, but he knows that stench;

"You smell like Strange."

A closer look at Tim is owed; Trevor peers at the cat, at first wondering if it's Strange who transformed himself into an animal to spy on people and get a free meal. People change into animals all the time; look at Adrian.