Carol

Carol is Scrooge's partner. Another one of GHQ's test subjects until she escaped with Scrooge.
Carol is the only character shown to house a variety of Voids. Every time Scrooge draws out her Void, it manifests itself as a different weapon. Carol is also impervious to Scrooge's imperfect Power of Kings' drawbacks, meaning she actually survives having her Void drawn by him instead of immediately succombing to to the Apocalypse Virus.