Origin?

Rockman claims to be from a land far below the surface called Abyssia. He ruled with his wife, the Queen and daughter, the Princess. Life has happy and peaceful. The people loved them.

One day The Evil One came and brought war to his land. Rockman and his people went into the fight without any hesitation. Their home was worth fighting for no matter what.

As they fought, the Evil One kept leading them further away, always out of their grasp. One day Rockman was separated from his people in chasing the Evil One. Alone in the dark tunnels, he could not go back to his home. The way was blocked off.

Searching for years, Rockman eventually found his way to the surface. He decided to do as much good as he could in the name of his people. Each night he pounds on the ground in the hopes that they will hear him.

Knock, knock

Revived in the modern day, the group tries to adapt to their new world. Rockman continues to pound on the ground each night to someday get back to his princess.

Or this?

The mining company would go to great lenghts to fight daniel's efforts in uniting the town.   Finally the word got out that the owner of the company had hired some men to kill Daniel down in the mines in order to send a message to the others.  Daniel refused to stay away.

Entering with some of his buddies, a fight broke out.  When it was clear that Daniel would win this fight, the owner took off.  He had a back-up plan, explosives.  The mine exploded.  It was a bigger explosion than planned.  Everyone died but Daniel seemed to have been exposed to some gas that made him invulnerable.  When he finally dug his way out, he discovered that the entire town had collapsed into a sinkhole.  Everyone in the town, including his wife and child were dead.

When Daniel was found, he was pounding on the ground in torment.  At night he would walk around the ruins claiming he could hear his family calling him from beneath the ground.

When Colonel Dexter saw the old photograph the woman had, he told her that it wasn't him.  It turns out the man in the phtograph does look quite a bit like Rockman.  Dexter figured if it was true, it might be better for Rockman this way rather than knowing he'd never see his wife and daughter again.