So Deirdre actually ordered, received, and starting playing Fallout 3 a little while ago, but I haven't written anything about it.
Summary: She is playing a usually-good character, usually helping people but sometimes doing whatever she wants. She has taken the Bloody Mess perk, and laughs when her targets explode in a flurry of blood and limbs. She often says such things as "yeah suck it I crippled your FACE."
Fallout is much more based on numbers and character-building than Bioshock, and infinitely more than Half-life. So not everything is super intuitive, like where to put points when leveling up. I have told her to just read the descriptions and then put points wherever she likes.
She really likes exploring, so the game is perfect in that regard, since its world is almost intimidatingly huge.