The Plausibility Factor (thinking out loud)

I have my protagonist as a Shakespeare quotin', intelligent, witty, stubborn young women living in the 17th Century. However, from the age of thirteen to seventeen, she was in a tollbooth cell in Forfar, Scotland, having been accused of witchcraft. Her mother, among others, was executed - strangled and burnt to ashes in a barrel of tar. Now, how do I make this character a Shakespeare quotin', intelligent, witty, stubborn young women? Is is plausible considering this history? Well, I don't know. Certainly good writing can make it so, but for a first novel, am I asking too much of myself? I'm stalled.

How do I make myself believe my character? Oh, I can justify how she knows Shakespeare. I can justify her intelligence and wit. But would she have those traits? Four years is a hell of a long time for a young girl. She lost most of her youth to a dark cell. She would be malnourished among other things - certainly that could affect her thinking.

Hmm, second-guessing is painful. I have to fix this.