Vivian (Paper Mario)

Vivian is a Shadow Siren from Paper Mario the Thousand Year Door. She started out as a member of the Shadow Sirens who worked for the main villains, but afte suffering a few too much abuse from her sisters, she decided to stay with Mario since he had shown her some kindness. Vivian became the 5th partner for his party.

Ultimate Story
Vivian, being one of Fanfictiondreamer's favorite partners in the second Paper Mario game, decided to make her an important character in the story and she had played a massive role in the story.

Vivian was part of the Secret organization of Darkness, the Descendants of Darkness, even though she wasn't involved with their plans.