Answer:
Goes over all the hills and hollows. Bites hard, but never swallows.
What is given but kept by the giver?
I always follow my brother but you cannot see me, only him. You cannot hear him but you can hear me. What are we?
A hill full, a hole full, yet you cannot catch a bowl full.
I have one, you have one. If you remove the first letter, a bit remains. If you remove the second, bit still remains. If you remove the third, it still remains.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.