Dresden Files Cooperative Card Game promotional/exclusive event cards
At the time of this writing, BoardGameGeek's list of expansions for the game show that the following are the only promotional cards that have been released:
Mouse &amp; Variants

An Evil Hat webstore exclusive for the Dresden Files Cooperative Card Game! Bring Harry's faithful companion Mouse (with a dash of Mister) into the game with this character deck packet. Also includes 2 variant cards for Harry's deck and 3 variant cards for Susan's deck to add a little variety to your play.
–Store page

Ra Crossover

An Evil Hat webstore exclusive for the Dresden Files Cooperative Card Game — and a crossover with Greater Than Games' Sentinels Comics universe! The sun god Ra steps into a new avatar in the Dresdenverse with this fully playable character deck. When one supernatural fire-slinger isn't enough, it's time to call down the flames!
–Store page

Both of these were also available as Kickstarter promotional items before being made available on the web store.
It sounds to me like the Mouse &amp; Variants pack is the one you are thinking of with a female character on them, given that it contains 3 variant cards for Susan's deck.