This finicky feline started as a thief, fell in love with a hero and became his partner, then after they broke up sided with villains against him but saved his life at the last minute. While she originally had no super-powers, she later gained an ability to manipulate probability fields.

Felicia Hardy is the Black Cat, and her origin precisely matches this description. She started as a cat burglar, fell in love with Spider-Man and became his partner, later broke up and sided with villains but ultimately saved Spider-Man's life. She originally had no powers but later gained the ability to manipulate probability fields (bad luck for her opponents). Selina Kyle is Catwoman (DC), Greer Nelson is Tigra (Marvel), and Sharon Smith is Catseye (Marvel).