Answer:
I only exist when you are here. Where you never were I can never be.
You can read me both ways I wear; One way it's a number reversed a snare.
When I point up, it's bright. When I point down, it's dark. What am I?
My first half means container. Not a lot of people understand my language. What am I?
I am black, white, and read all over. What am I?
For our ambrosia we were blessed, By Jupiter, with a sting of death. Though our might, to some is jest, We have quelled the dragon's breath. Who are we?