Answer:
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
I'm the source of all emotion but I'm caged in a white prison.
What is easy to get into, but hard to get out of?
I am rarely touched but often held. If you are smart you'll use me well. What am I?
My first is high my second damp my whole a tie a writer's cramp.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?