She is older and more mature than her childish appearance would suggest - the exact opposite of Celestine. Having been trained from a young age to be Zephie's bodyguard, she has learned to repress her emotions and to always act in a level-headed manner. Clever, cunning, and fearless, her training has given her a black and white view of the world. As a result, she dislikes breaking rules and promises, and has a hard time seeing things from another person's perspective.
Rue appears as a young slim girl, short in height, and has short blonde hair and purple colored-eyes.
Rue first appears in the intro scene of MagnaCarta 2 where she helps Zephie break out from her prison after Schuenzeit kills her mother and usurps the throne. The pair escapes from the castle, fleeing south to the city of Abazet to join forces with its ruler, Count Alex. There, they formed the Southern Forces to liberate Lanzheim, and rise up against the Northern Forces.
A year later, during the Lanzheim Civil War, she was sent to Belfort by Zephie, desperately trying to uncover information on the Sentinels, mysterious 'living' mechanical weapons that have been destroying the Southern Forces units, causing them to retreat. Rue succeeded, but Alex secretly informed Scheunzeit about it and in turn sent Elgar to eliminate Rue who stole the information. When Elgar intercepted them one last time, Rue tries to defend Zephie, but she was quickly overwhelmed by Elgar's power. When Elgar raised his sword to deal the finishing blow to Rue, Zephie stepped in to protect her, taking the stab to her stomach.
Rue yells at the Princess while clutching her wound, but somehow surviving Elgar's attack, Zephie's body was enveloped by a mysterious blue light and unleashed a powerful attack on Elgar, breaking his white glasses and knocking him out. Unseen by the player, Zephie escapes with Rue to Abazet.
Two years later, Rue was sent to an espionage mission in Belfort and was not seen until near the end of Disc 1 where she returns to Abazet, telling the Southern Forces with information regarding the Sentinel's manufacturing process, and news that the Northern Forces have withdrawn most of their troops from Highwind Island.
Siara is an Indian and Arabic word meaning "Unique" or "Pure, Holy". Tessia is an old greek name meaning "Hunter" and "Guardian". Her nickname Rue means "To Regret" in English.
- Despite having a pumpkin chain on her backpack in her concept artwork, it is never seen in the game.
- She is voiced by Ayako Kawasumi and English dubbed by Kate Higgins.