Roxxi used to be a punk hell-raiser as a teenager, taking great delight in creating wanton mayhem and chaos, but mellowed out as she got older and sobered up, eventually opening Existential Thread - an underground boutique selling armor and clothing to the adventurers passing through New Vegas, as well as chemical substances on the down-low. I picture her as a laid-back, unflappable, and laconic character - real chill and doesn't use a lot of words when just a few will do. She doesn't speak in complete sentences, and is casually foul-mouthed. I think a voice with vocal fry would suit her character well.