This is one of the main ways that cats are different than dogs - dogs are inherently trusting, but cats? You have to earn the trust of a cat. A lot of people get purrfectly upset when they bring a cat back for the first time because most cats will hide for at least a few hours upon arriving to a new home. But for all of us feline expurrts, we know that this is normal.
Cats need time to adjust to a new environment, even if it's one that is full of love. Many will mistake this for the cat not liking them, but it's all just part of the kitty's process.
Some cats take longer than others to warm up. It's not uncommon for especially shy cats to take weeks, even months, to come out of hiding. Unfortunately, a lot of cats are returned during this period because their hoomans weren't patient enough. However, if you can wait it out, the scared baby will eventually understand that you are purrfectly trustworthy, and then you will have a best friend fur life.
That's exactly what happened below - a loving cat purrson adopted a shy shelter cat, who spent months hiding in her home. Every night after work, she would read to the cat, or speak about her day, leaving treats for her to take after she left the room. Eventually, the cat came out, and now she's queen of the house.
source https://cheezburger.com/42768389/cat-purrson-adopts-shy-shelter-cat-spends-months-gaining-her-trust-with-no-improvement-until-the-cat