I had a sudden flash of inspiration while I was offline the past couple of days: if Dogstar is supposed to be the furry answer to Superman, then what about his contemporaries, Wonder Woman and Batman?
This is Bast, or at least her mortal avatar. We all know she's the Egyptian goddess of cats, but not as many people know she is also the sworn protector of women and children (which can be easily expanded to "the innocent") as well as the Egyptian pantheon's most staunch battler of evil. Sounds like prime superhero material to me...
In addition to her as-yet undetermined-by-me "divine" powers, her cobra bracers can lash out to incredible lengths and bind opponents as well as their hoods expanding into small shields. On her anklets are a pair of golden scarabs that enable her to fly using their wings.
As for her origin, I'm thinking something prompts the long-absent Bast to resume her crusade, so she possesses one of her temple statues and shrinks it to humanimal size, increasing its density and granting herself increased strength and resistance to damage, while using magic to make it otherwise indistinguishable from an ordinary felin.
Again, just some rough first ideas.