Princess Liana (simply known as Liana) is the main protagonist in the 2008 animated film, Barbie & the Diamond Castle. She is a Princess of Music who lives with her best friend Princess Alexa in a cottage deep in the woods.
She is played by Barbie and voiced by Kelly Sheridan, and her singing voice is provided by Melissa Lyons.
Liana was known as a poor gardener that was lived in the woods with her best friend, Alexa. They both share a love of music and sometimes they sing together along with their guitars. One day, a storm ruined their beautiful garden that they sell to make money.
One day, they are met an old woman, with a sack full of rusty things, when they were going to town to sell their the flowers left from the ruined garden. She shares her lunch with the poor, old woman. As a thank you, she wants her to pick something from her things, she first ignored it, but Alexa said that she will hurt her feelings, so she picked an old mirror.
They got back into their house and Liana washed the mirror, and it turned out to be a beautiful mirror with sparkly flowers with gold, swirly little stems. While they're both singing while they're clearing up the whole mess, both of them heard that someone is also there with them. It turns out that there was a girl inside the mirror. Her name is Melody, and the trio embark on they journey to a hidden Diamond Castle, where she studied as an apprentice. Along the way, Liana and Alexa found two little puppies on their way to the Diamond Castle.
Liana and Alexa has arrive at the village to be attracted to a inn. She and Alexa are both hungry, but like she explained to Melody, they had no money. When Edger comes out and talks about Ian and Jeremy late, Liana fibs and tells him she and Alexa are replacements. Edger agrees for their price, food. She and Alexa sing, "We're Gonna Find It" which gains the audience's and twins, Jeremy and Ian's attention. Their beautiful singing gets Melody to softly sing along though, leading Slyder and Lydia closer. Liana and Alexa meet the twins, and think they're being funny and are full of themselves. Liana gets bored of this and says that they were leaving.
Soon after, they are walking in the forest when Liana notices Sparkles barking. Slyder lands in front of them and they turn to face Lydia. Liana holds out Melody and Lydia insists she give her the mirror. Liana says no, protecting Melody. Lydia then tries to cast her spell on them but the necklaces protect the girls. Liana yells for Alexa to run and Slyder chases after them. Ian and Jeremy soon save them and leave Slyder behind. Liana asks where they came from, but then embarrassed, thanks them. She introduces herself and Alexa then Melody asks if everyone's okay.
It was assumed Melody's story was explained for Jeremy and Ian then are taking the girls to the Seven Stones. The puppies run off though and the friends chase after them. They meet a troll who knows Ian and Jeremy and wants to eat them, along with the puppies. He gives his riddle and Liana thinks. She pulls out Melody, who can't think of the answer either. Liana thinks of it the last second, your voice. The trolls disappears, freeing the boys and creating a bridge. Liana is surprised as Alexa to find its real. They step on but it starts to take them away before the boys can reach them.
It seems to have been a while later when Alexa can't go any further. Liana asks if she's okay. They come across a beautiful mansion and don't see the servants are under Lydia's spell. Liana believes them and she and Alexa explore. Liana is first excited then remembers that they need to take their new best friend, Melody, to the castle. She and Alexa start to fight, while Melody pleads for them to stop. Liana eventually leaves Alexa at the mansion, much to Alexa's shock and tells Melody they're going to the seven stones.
Liana and Melody reach the stones but Melody wishes Alexa were there. Liana starts to talk about Alexa with frustration that eventually withers down to her upset. When both girls are distracted, Slyder grabs Liana and the mirror, leaving Sparkles behind.
Liana is quite tied up and refuses to speak to Lydia. Lydia finds Liana stubborn and calls for Alexa, who is now under her control. Liana yells for her friend but Lydia insists Alexa can only do what she wants. Liana is helpless and can't stop Alexa from nearly walking to her doom. Thus, Melody is forced to act and save her. Lydia takes Melody and Slyder throws both girls of the cliff.
Liana hangs on to a branch and Alexa at the same time then heaves them to a platform. She nearly cries, apologizing to Alexa when she sees Lilly above. Lilly drops Alexa's necklace, which Liana catches. Liana broke Lydia's spell and explained to Alexa about how Lydia captured Melody.
Along with the boys, Liana and Alexa go off to rescue Melody. They arrive and Liana and Alexa pretend to fall under Lydia's spell, fooling Lydia and Melody. Liana grabs Lydia's flute when she is close and holds it over the water, implying she wanted to trade it for Melody. But Lydia grabs the mirror and threatens to smash it, resulting in Liana about to give the flute. Melody then surprises everyone by breaking herself. Liana tells Alexa to save Melody, who Lydia threw in the pool. Liana holds the flute until Lydia lunges for it. She and Alexa watch in shock as Lydia seems to be defeated.
All are saddened by Melody's sacrifice but Liana still thinks the Muses Instruments would bring her back. After Jermey asks, Liana remembers that Melody sang about believing in things you can't see, including the castle. She and Alexa sing and the castle returns. Both girls earn dresses but receive the best gift of all, Melody is free.They all hug and go into the castle.
They reach the instruments and Melody says that once played, will bring the muses home. However, Lydia swoops in and attempts to destroy them. Liana plays the harp while singing along with Alexa and Melody, defeating Lydia once and for all. She and Alexa become princesses of music and dance with Ian and Jeremy, Melody and the other muses happily watching.
Both girls along with their puppies leave the castle in a carriage with Melody waving goodbye along with the twins and they get taken home. Liana plants the magic seeds which grow into beautiful flowers with diamonds in them. Liana and Alexa are seen throwing flowers to Ian and Jeremy and are lastly seen skipping back to their cottage, happy that their story has come to a close.
- Her name in Germany is Delia, which is the name of one of the princesses in Barbie in The 12 Dancing Princesses.