Origin of name:
The Princess Who Never Smiled - Wikipedia, the free encyclopedia (it's Euna in the myth, but I like the spelling Yuna better cos it's easier to tell how to pronounce it)
Name: Yuna
Age (between 10-21): 16
Sex: Female
Sexual Orientation: Lesbianian
Old Injuries/Scars/Tattoos: Scar down left side of face which apparently doesn't impair vision, somehow.
Personality: Yuna is a calm and quiet entity. She is quite shy, and doesn't speak much. Yuna's bipolar alter-ego, often referred to as Naiyu as a reversal of her name, is pretty much the opposite. Loud, rude and outgoing. Both personalities have a strange fondness for the concept of eternity, though both go about assuring it in very different ways. The two personalities cannot directly speak to one another, although they are aware of each other's existence. When they do converse, they take it in turns to control the mouth and vocal chords so to an observer it would look very much like Yuna was speaking to herself while alternating between mild and aggressive tones of voice.
Biography: Yuna was one of those street kids. She ran away from home at age 14 and quickly immersed herself in the world of gangs, violence and murder. Of course, back then, she had only one personality, which was pretty much Naiyu with slight traces of Yuna. As such, you could say that while Yuna is the dominant one, the real one is probably Naiyu. Back then, the pre-Yuna/Naiyu (referred to from now as Girl A) had the gang name "White Rose", for beneath her pure exterior lied one of the most savage and thorny hearts in the city. Though she has never killed someone in person, she's planned so many successful deaths that the other 4 gangs have pretty much completely dissolved. Now that the White Rose had disappeared without a trace, though, the other gangs are beginning to re-emerge and fighting over control has resumed with more force than ever.
After Girl A was chosen by the researchers, they performed a series of procedures on her that would suppress her memories of being Girl A to try and diminish her phenomenally large rebellious streak. While it did indeed reduce her attitude, the memories became a kind of trauma point and forced the separation of the Yuna and Naiyu parts of the personality as a defense mechanism. To this day, neither of them recall those past 16 years, nor can either of them remember even their original name. Now, the brain is a fascinating machine and it will often actually create new memories where there are none. Both of them believe they have been in the research facility their entire lives, and neither of them realises that two personalities in the same body is strange.
Developing Ability: Belief Projection: [spoili] Yuna can alter reality to suit her imagination. Or rather, she likes to pretend she can. In truth, she can only alter reality to include things that she truly believes to be real. She could not say "There's a dragon over there y'all" to create a dragon, unless she was truly able to convince herself that there was a dragon over there. As such, the reality altering is usually very minimal in scale, for example if she had done an algebra question and come to the answer X = 2, as long as she doesn't doubt this answer, then the answer to the question will become X = 2, even if the original answer was supposed to be X = 4,117. So in summary, if she doubts something she is trying to project, then it will not form.
There is a second part to this ability, though, which is reality deception through input. If someone who wasn't Yuna but had a strong relationship with Yuna (eg, a close friend) were to say "There's a dragon over there y'all", then a dragon would come into existence over there. It would not be a real dragon, just an illusion of one. That is, it would look, sound and smell like a real dragon, but you could not touch it and it could not touch you. [/spoili]
Tl;dr - Yuna can create illusions if a friend describes what the illusion will be. If Yuna genuinely believes something to be true and has no doubt about its existence, then that thing will exist. The second part of this will likely never come up in the RP, as Yuna is a very cynical person.