They come around sometimes. You don't know what they've been through so maybe once she gets to know you she'll be more affectionate.
Godiva wasn't super affectionate either at first; she spent about a week just hiding after I brought her home. But eventually she became like a little puppy, following me around everywhere and just wanting to be wherever I was. She never did warm to being picked up; in fact she absolutely hated it. But if I sat down to watch TV she'd sit right next to me.
My "new" cat Loosie isn't quite as much of a "puppy" but she likes to be picked up, or more accurately, wants you to pick her up so she can sit on your shoulder. Of course since she weighs 17 pounds, that doesn't last very long.
Anyway, bottom line is that all cats are different. My advice is just give Violet a few weeks until she gets more comfortable in her new home, then maybe you'll have a better idea of her true personality.
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"The cat is the most ruthless, most terrifying of animals." - Spock in the "Catspaw" episode of ToS Season 2.