Fray felt like B and seemed normal to have in the dream so Faith pretty much linked her up as a slayer in her head. It didn't matter whether they'd get along or what kind of person she might be. Faith's first instinct was to kick a little ass for her because in some way they were the same.
Now if you said that to her when she was awake it was quite possible Faith would kick your ass for you.
"Why should we? Hell, if she wants to have a cute hold hands dream I say go for it. Why on earth would we cater to what you want." She got up off her chair to stalk around a little. "Now, if it were me it'd be a biker bar and booze but hey not everyone can live my life."