Grandpa Joe is ninety-six and a half and still hopping around and chatting his face off. Not your average grandpa, we'd say. He starts the story bed-ridden, but the excitement of touring the chocolate factory gives him the energy he needs to get out of bed, and even dance!
But even when he is still stuck in bed, the factory brightens his day. When Charlie asks about it, Grandpa Joe is the one to tell us all about it: "'My dear boy,' said Grandpa Joe, raising himself up a little higher on his pillow, 'Mr. Willy Wonka is the most amazing, the most fantastic, the most extraordinary chocolate maker the world has ever seen!'" (2.6). He loves to tell stories, as any good grandpa would, and as it turns out, Mr. Willy Wonka makes for some great yarns.
Grandpa Joe is very excitable. We see this when he jumps out of bed and starts dancing (12.9) but also throughout the factory tour. On the ride in the great glass elevator, you'd think he was putting on a one-man show with all the questions he asks and screaming he does. Grandpa Joe is just as excited to be in the factory as all of the children, and can you blame him? He's had a tough go of it in life, and the chocolate factory is a nice break from the unfriendly outside world.
When he tastes the chocolate river, he says it's the "'creamiest loveliest chocolate I've ever tasted!'" (18.19) – that could have come from Charlie's mouth just as easily. And just like a child, he's more tolerant of people who are, well, a little different. He's the only adult who doesn't call Mr. Wonka crazy, and in fact, he defends him: "No, he is not!" he shouts (18.38), after the other adults call him a whole slew of crazy-related adjectives.
Most importantly, Grandpa Joe loves Charlie. He serves as Charlie's confidante and rock (literally – Charlie has to hang onto him in the elevator). He's always looking out for Charlie, and trying to bring him a little joy. When Charlie's birthday chocolate bar comes up empty of a Golden Ticket, Grandpa Joe gives Charlie his "secret hoard," a "single silver sixpence" (9.2), so that Charlie can have another crack at finding the prize. When they find no Golden Ticket hidden inside the wrapper, Grandpa Joe and Charlie "burst into peals of laughter." (9.25) It almost seems more like they're friends, than a grandpa and his grandson.