My friend is convinced along with his family that rare steak does not contain blood but is just meat juices. I am convinced that it does contain blood. Does rare steak contain blood?

I'm afraid not, almost all blood is drained from the cow at slaughter. The blood red color in the beef is due to lots of oxygen holding cells in the muscle (myoglobin), not blood cells.

Most of the juice that you get off is water (beef is 3/4 water) mixed with some of the proteins.

My dad still believes it at least has some blood even if its mainly water and proteins. There is still at least some blood left right?

Well yes of course there will be a tiny amount, but the vast majority is not blood.

How can they possibly drain all blood from capillaries? I could understand major veins/arteries...

They stun the animal (cattle with bolt guns, smaller animals with an electric shock through the brain). This renders them unconscious, but they are still alive. They are then hung upside down and their jugular vein is sliced. The heart is still beating, so almost all of the blood is drained from the body.

They get vampires to suck out the blood.