Answer:
I jump when I walk and sit when I stand.
I hide in a dark tunnel awaiting my time. I can only be released by pulling back. Once released I may do unstoppable damage.
I have a brother. However much we run we do not reach each other.
I am black and white and full of fuzz
I come in variety of colors and am found almost year round. My house is tall and my only fear is the cold. What am I?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.