Sounds like he is fearful, which makes me wonder if given time and giving him space to let him do what he feels like doing without moving into his face, like petting or anything like that, he might warm up. Have you talked to your vet about it? Maybe some medication's?

@ksdm Nine days is not all that long for a cat to adjust to a new environment. Cats are funny creatures and it's so difficult to understand their motivations. He sounds to me like your new kitty is still very frightened. I've had cats for many years and I've also fostered cats for my local animal shelter. What I do with a new cat that I've adopted and especially with foster cats is that I give them their own room for awhile and go in and visit with them. Eventually, and it could take many days or weeks these cats, if already socialized and lived with humans in the past, will warm up and will start coming out when I enter the room. I also learned that some cats will let you know that they are overstimulated and have had enough petting when they bite you. It's not pleasant but I learned with one of my cats to watch her carefully and look for signs that she was overstimulated. She let me know by twitching her tail and beginning to draw her ears back. So I withdrew from her first.

So I'd like to suggest that if it's at all possible please give your new kitty more time to adjust and give him his own space for awhile.