[@sassy1085]Here's an idea I came up with:

A really nice, innocent girl who had travelled the world with her parents (due to their occupation or something) but along with all the wonders of the world, she saw how much suffering there is in the world. Thus when she got her Diary, she decides to try and win to make the world a much nicer place. However, she doesn't realize what being in the Survival Game really entails and is basically blinded by optimism on the onset of the Game. As the Game progresses, she slowly realizes how nasty and dark the games are and how she basically make other people suffer for her "greater good". 

In a similar vein, she doesn't have much in terms of direct combat skills, but she has picked up several survival skills along with vast knowledge in different languages and cultures along with a really charming, innocent personality, of which changes as she realizes how hideous the Game is and starts to question if her "greater good" is worth all the chaos and suffering that the Games cause. As such she either abandons her idea and sees the world in a new "whatever it takes to win" light to achieve her "greater good" and hardens up and becomes a much darker person overall or she starts slipping as she keep telling herself everything is for the "greater good".

Just an concept I came up with to hopefully give you some ideas, don't need to copy it word for word if you don't want too. If you do however, feel free too.