I know there are a girls out there who don't do anal (or other things) in their scenes that they will do in private because they're waiting for the "right time" to start doing them in scenes.  Sometimes, the "right time" is when they stop getting hired to do scenes, or the "right time" is when they get offered enough money. Or the "right time" is because they really want their co-star to do them anally... And other variations on the theme.

It goes the other way too.  Just because they do something in a scene doesn't mean they'll do it in private. There are quite a few girls who will do anal on the screen but not in private.  Same for kissing, and even bbbj - some porn stars will do bbbj in scenes but insist on condoms during privates.

Oh, and for anal, a lot of times the girls need advance notice because they have to prepare.

The basic thing is it's her rules.  You can ask.  She can say "yes" or "no" or "for more money" or whatever, and you take it from there appropriately...  So, book a date with Brooke and ask.  The worst that can happen is she'll say "no".  But, I'm sure you'll have a good time anyway. :-