I come freely, but won't leave without effort. A friend, I should not be. I have an opposite, who cares for me. I have no concerns, or uncertainty. This riddle is written is to dispell me. No alternative to me as far as I can see, I thrive on the consistency.

I carry messages no one wants to say aloud. I stand politely between two storms. I translate tension into ‘let’s circle back’ I belong to both sides And fully to neither. Call me the elegant middle child.

Onestone in German, man was I genius, Nobel Prize winner, but not for what made me famous, Photoelectric effect, and gravity is just spacetime curved, I didn't get as many Nobel Prizes as I deserved

Three: container, able to do Three more: olden 'there,' place out of view Gouge or scar, in Earth face hewn

I guard your toes from mud and rain, March through puddles without complaint. On farms I rule, in armies too, Sometimes I’m kicked when dreams fall through. What am I?