When Caine was a child, the princess and heir to Corona was kidnapped and the King ordered the guards to arrest all the criminals in the kingdom, as he believed that one of them had something to do with his daughter's kidnapping. One of the criminals was a petty thief, Caine's father. Caine was enraged with her father's arrest as he had nothing to do with the Lost Princess's kidnapping and spent the rest of his life in prison, until he passed away.
Over the years, Caine became "Lady Caine", the leader of a pirate gang and well known in the thieving and crime community - as Eugene knew who she was and has many criminals willing to serve her.
Lady Caine bided her time until the opportunity to exact her revenge presented itself in the form of Rapunzel's coronation, in which she was disguised as the "Duchess of Quintonia". On the day of the coronation, Caine made her way to the castle's dungeon so she could free her crew of other criminals that also want payback at the King. When they made themselves known, the crew captured a hand full of nobles and Lady Caine told Rapunzel what her father did to hers before she ordered her men to take the King away. So he and the other captured nobles would know what it is like to be locked up and taken away from their families.
Rapunzel however won't going to let Caine or her crew take her father away, so after she used her long hair to free the captives, Rapunzel, with the help of Eugene and Cassandra battled with the gang of criminals. Cassandra faced Caine with a candle stick pole, while the pirate leader faced the handmaiden with two fans that possibly contain blades. With her crew defeated and the Lady Caine running out of options, she grabbed the only weapon that she could get her hands on, which was used to lock the door and keep the guards out; when Caine realized her mistake it was already too late. She and the rest of her crew were arrested for their past and recent crimes, and were brought back to the dungeon to serve their sentence.
In "Max's Enemy", Caine is shown to still be in prison, though her connections in the criminal underworld would act as her means of escaping unnoticed; she enlisted the thief, Dwayne, and her horse, Axel, to infiltrate the castle and break her out. The two succeeded in the mission almost without notice, but Maximus eventually caught onto the scheme, as did Rapunzel. Together, the two were able to apprehend Caine and Dwayne, as well as Axel.