Charley's grandfather Edwin was an engineer who worked on the giant robots who provide for all of humanity's needs.
But a few years after Charley was born, he grew… shall we say, disillusioned with his job at RoboCo. So he loaded up his old truck and started driving, ending up as far away from the robots as he could get. He's been off the grid since Charley was a boy, so they've hardly seen or spoken to each other since before Charley can remember.
Completely self-sufficient, Gramps has no need to take any crap from anyone, least of all Charley. But he’s also the first to help out whenever someone needs a hand, and his mechanical skills are still in use when he repairs his neighbors' aging appliances and gadgets.