Paulie is the wife of Earth's Mark Lister. Very early in the novel, we learn that Mark neither likes nor trusts her. They met when Mark showed up out of nowhere, full of both magical and IT talent, and was taken under the wing of Paulie's American flatmate at the time.
Both women were members of a secret magical coven, and they saw to it that Mark was initiated into their group as soon as possible, although he rose much higher in the overall organization than either of them ever did. Paulie knows that Mark has a responsible position, but he tells her very little about it, and creates alibis and false obligations to cover up any trips he takes as part of it.
Eventually it turns out that Paulie herself is being stalked and shadowed by a spy from Arth, whose job it is to report any news about Britain's magical adepts. Which does hardly any good, since Mark is so secretive. Basically, just about all we see of Paulie in this novel makes it clear she's a vain, possessive, jealous woman who spends most of her time complaining about how difficult her life is.