Rudgrin

Rudgrin is the daughter of Lord Bleak and is consequently the princess of the Darklings.

Biography
Sometime after Lord Bleak was overthrown by King Regal and Queen Jemma and banished across the Black Sea, he had a daughter. Rudgrin was raised as the Darkling Princess and grew to be intensely loyal to her father.

The Ruby Princess Runs Away
The Darkling Lord comes up with a plan to take over the Jewel Kingdom as revenge: his Darklings will kidnap and replace each of the Jewel Princesses one by one, starting with the Ruby Princess, Roxanne. He gives Rudgrin a magical shape-changing mask that will make her look exactly like Roxanne and sends her across the sea with an escort of Darklings, so that they may kidnap the princess and replace her with a disguised Rudgrin.

On the way, they come across the two gnomes who have forged the ruby crown and attack them, injuring one and stealing the crown so that Rudgrin will appear more convincing. Rudgrin continues to travel to the Jewel Palace in a beautiful glass coach and even has her Darkling escort disguised as knights, announcing her as the Ruby Princess.

The Darklings expect that they'll have to kidnap Roxanne, but are happily surprised to discover that she has run away. Rudgrin plays the part of Ruby Princess well enough to be welcomed by the royal family, relieved to have "Roxanne" home safe. The coronation of the Jewel Princesses proceeds and soon Demetra, Emily, and Sabrina are all crowned. The great wizard Gallivant is just about to place the Ruby Crown on Rudgrin's head when the doors burst open to reveal the real Roxanne. Although her dress is torn and her hair is tangled with thorns, she regally declares that she is the rightful princess and that Rudgrin is an imposter. She tells everyone that Rudgrin is the daughter of Lord Bleak and wearing a shape-changing mask, but Rudgrin accuses Roxanne of being the real imposter and orders the guards to arrest her. The whole court stares in shock, unable to discern who is lying. Queen Jemma deems that Rudgrin looks like her daughter, but the messy Roxanne with the ripped skirt and dirty face acts like her daughter. After some confusion, Gallivant announces that there is a way to determine the true Roxanne: each princess is born with a mark in the shape of her jewel. Whichever girl bears the mark must be the true princess. Rudgrin can only stare in confusion, but Roxanne smiles confidently and raises her right arm so everyone can see the teardrop mark on her wrist. The other Jewel Princesses raise their wrists too, showing their own marks. Twitter, the palace secretary, orders Rudgrin to take off her mask and peels it off himself when she doesn't, revealing her twisted, ugly face to the whole court. Instantly, the guards whisk her out of the throne room.

In the short film, Rudgrin is played by Molly Bauckham. Despite Rudgrin never singing in the film, Bauckham had dubbed the real Roxanne's singing voice.