Answer:
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
A man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?
Today he is there to trip you up. And he will torture you tomorrow. Yet he is also there to ease the pain, when you are lost in grief and sorrow.
People are hired to get rid of me. I'm often hiding under your bed. In time I'll always return you see. Bite me and you're surely dead.
Often cooked as fillet, this meat comes from an animal that swims underwater.