Race: Cat Sidhe. Unlike most of her kind, though, she is an extremely fierce fighter. Her larger form will probably be a tiger.
Sexuality: Lesbian Switch (May be willing to have a go with males, but it depends on the character and writer)
I'd like her to have a strong relationship with both the princess and the queen, so I'd like to tie in her back story to the royal family. I'm thinking that she was one of the many heirs to one of the stronger kingdoms that the Red Queendom conquered. She helped destroy her own bloodline by assassinating her father who ruled (perhaps along with some of the other heirs). She then fled to the Red Queendom, surrendered herself to the queen, and gave her all of the necessary information to conquer her own people. She followed every further order to the extreme, and she became one of the few to earn the queen's trust. Her fighting skills are powerful, but she spends most of her time guarding the princess or patrolling the castle. Maybe she serves the queen as an assassin or spy at times, considering her elusive forms?
She idolizes power and is infatuated with the queen because of this. She always tries to always impress her and get into her bed. She loves the princess as well, but in a different sort of way. Since the princess is weaker, she enjoys toying with her. Of course, she would still give her life in her protection, but she enjoys stretching the boundaries of what she is allowed to do to the heir. She loves teasing her, but she also thinks that it will make her stronger in the long run.
I was thinking about, instead of the part about her being part of a destroyed nation, making her previously be some sort of guard for the White Queendom. She defected, spilled some info, etc. The only problem is, since it has only been three months, I'm not sure if that is enough time for her to prove herself as loyal and then make the connections.