Some cats take longer to open up than others, and that's purrfectly okay. Cats need to move at their own pace.
Cats are very sensitive to changes in their environment, even if its bringing them to a home full of love and safety. To them, it's a new territory with new people and pawssible new dangers around every corner. This is why most cats after adoption will run and hide for a few days. It's purrfectly natural. They're sussing out their new space, trying to understand the rhythm, where is safe and where is scary, and adjusting to life around new hoomans. They will eventually learn to trust you and their new home, but you have to give them the time they need to properly decompress and open up.
Some cats are better than others, and some cats are extremely difficult cases, like our void below. The shelter warned her new pawrent that she was extremely anxious (relatable), the only way the cat could be touched was if she was wrapped in a purrito, for everyone's safety. She adopted her anyway because if she didn't, who would?
It took a lot of time, and a lot of patience. A lot of hunger strikes, until one day, the scaredy cat decided to test the waters and take some food from her hands. Even after that improvement, every noise had her running back to her hiding spot, and yet, the pawrent purrsisted. Now, the cat confidently walks around her house, begs for food, and falls asleep on her chest every night.
They say good things come to those who wait, and that's especially true with cats. Some felines need a lot of time to open their hearts, but once they do, you'll never know a love more purrre and heartwarming.