Olivia

Olivia is Mario's main ally in Paper Mario: The Origami King, taking a similar role to Kersti in Paper Mario: Sticker Star and Huey in Paper Mario: Color Splash. She is King Olly's younger sister, although it was later revealed that he essentially created her. She can transform into a Vellumental on certain Magic Circles. This can be done on the field or in battles.

Background
Olivia was designed by Origami Craftsman as a part of an Origami Castle built for the Origami Festival. Her elder brother, Olly, the Origami King, was folded before her, but Olly turned against his creator and trapped him in the wall of his workshop. Olly then created his sister, Olivia, as part of his plan to rule over the Mushroom Kingdom, sitting in the throne beside his to act as the queen to his king. However, Olivia rebelled against Olly's plan, viewing it as her duty to stop him and believing that origami and flat paper can live together. She tried many times to change her brother's mind, but with no avail. Eventually, King Olly punished Olivia by trapping her in a wall in Peach's Castle.

Paper Mario: The Origami King
When Mario explores the dungeon in Peach's Castle, Olivia calls out to him, saying she is stuck in an "in-between dimension". Mario uses the 1,000-Fold Arms to free Olivia sandwiched in between the wall sheets. Together they explore the castle dungeon and eventually find a trapped and folded Bowser. The trio goes outside onto the castle's balcony where they meet with origami Peach and a yellow origami Shy Guy. After a fight with some Folded Soldiers, the yellow Shy Guy reveals himself as King Olly. Olivia is horrified to see her brother and realizes that he is behind everything. She tries to convince Olly to give up, but her brother doesn't listen. After revealing his plan, King Olly summons five streamers that wrap up Peach's Castle and lift it to the air. Mario, Olivia and Bowser manage to escape but they get separated in the process. Mario and Olivia together land in Whispering Woods.

Olivia travels with Mario on his journey, explaining the battle system and how to fill in Not-Bottomless Holes. Olivia was responsible for naming Bob-omb "Bobby", and enables Mario to use Magic Circles. Olivia is usually very cheerful, but when Bob-omb sacrifices himself to save her from a boulder in Sweetpaper Valley, she becomes depressed. Olivia only cheers up when Mario uses a Goomba Mask to make a funny face, making her realize that Bob-omb wouldn't want her to be sad. She can also take on the appearances of the Vellumentals, and transforms into a giant hammer for Mario to use in the final fight with King Olly.

After the battle, Olivia fears she went too far with her hammer attack on King Olly, realizing that she mortally wounded her brother. She notices the mark on his body and reads it for him, telling him that it is a sweet message from the Origami Craftsman. King Olly regrets his villainy and makes a final request to Olivia to fold his remains into the final crane for the Thousand Cranes technique to amend his wrongdoings. Olivia is deeply upset as King Olly dies. With the help of the Origami Craftsman, Olivia finishes folding the final crane for the Thousand Cranes technique. Olivia wishes to undo all the origami Olly ever folded. This also erases her existence, since Olly was the one who first folded her. At the end of the game, Mario reminisces over Olivia while he and Peach watch fireworks.

In the game's 100% ending, a miniature, inanimate version of Olivia appears in the scaled-down model of Origami Castle, alongside a similarly scaled down version of her brother, fulfilling the role their creator had originally intended for them.

Super Smash Bros. Ultimate
Olivia makes an appearance in Super Smash Bros. Ultimate as a spirit obtainable in a limited-time event from August 28, 2020 until September 2, 2020.

Personality
Olivia behaves like a kind, naive and cheerful child. She is very friendly and can befriend anyone, like when she and Mario meet Bob-omb, or Toads, and even Bowser's minions. Olivia is also very emotional and easily becomes amazed by many things. She also easily gets distracted from time to time when she sees something wonderful. Usually Olivia is really happy and sees the world in bright colors, but after Bob-omb's death she becomes heartbroken, at least to the moment when Mario cheers her up. From the beginning, Olivia believes that origami and flat paper can be friends and doesn't understand why her brother hates flat paper so much. She also believes to the end that Olly can change and she initially did not want to fight him. Olivia, despite being angry at him for what he had done, loves her brother, and mourns after his death.

Powers and abilities
Olivia has an ability to float in the air but she claims that she must work pretty hard to float even a little bit, so she is probably weaker than her elder brother as he can float much higher than her. However Olivia's main power is using the magic of origami, such as summoning the 1,000-Fold Arms for Mario or transforming herself into a Vellumental. She can also, like King Olly, fold other paper-beings into origami, like when she folded Bowser during the fight with King Olly. In the final phase of the battle against King Olly, Olivia can transform into a giant hammer by use of a special Magic Circle after it is reassembled. This ability was given to her by the Origami Craftsman during the visit to Mushroom Island.

Quotes

 * "My name's Olivia! You'd probably like to know a lot more about me and why I was trapped like that, huh?"
 * "I'm going to stop you, Brother. As your sister, it's my duty..."
 * "Well, Mario...it looks like we HAVE to check out Shogun Studios. It would be irresponsible not to."
 * "WOOOOOW! The Great Sea is SOOO big! This breeze feels SOOO good! *sniff* Why does it smell SOOO salty? It's so endlessly big... The only word you could use to describe it is EPIC! Well, that and "great," I guess."

Paper Mario: The Origami King

 * European website bio: "Olly's younger sister, Olivia uses her powers for good - teaming up with Mario to take down her older sibling. Olivia loves adventure, and will help you find the right path if you're ever stumped"
 * Gallery description: An origami gal with a kind heart. She's King Olly's sister but is teaming up with Mario to stop her bro's reign of terror.

Trivia

 * In the Japanese version, Olivia tends to finish her sentences with "ですわ" (desu wa), a stereotypical speech pattern often used by princesses, noblewomen and arrogant women in Japanese media, similar to how Princess Peach talks in Itadaki Street DS and Fortune Street.