Who am I

Who am I? This question rages in my head
Do I wear the mask of good or consider this wicked?
One half of me is light, some would even say meek
I'm polite and caring; I strive to speak sweet
I wish upon a star and have faith in fate
But for a knight on white horse I no longer wait

The other side of me is dark, I wear a veil of gloom
Tearful thoughts plague my mind, will I soon succumb?
Aggressive and territorial I seem on first glance
My tongue is sharp and biting I take things in my hands
Do I bring pain or violence to achieve my greater goals?

I'm like the devil himself, I take no prisoners, no holds.
Or am I a princess locked in a castle so tall?
One white knight to rescue, to come and save this fall.
Who am I? I'm not quite sure, I'm caught in this suspense.
Is my true identity the heaven or the hell I've built?