Granddad Chet is Bryce's grandpa and Patsy Loski's dad; he moves in with the Loskis when Bryce is in seventh grade. And little does Bryce know that this guy is going to help change his whole world.
One thing we know about Chet is that he's a seriously nice guy. He helps Juli work on her front yard, teaches her how to build a fence, and keeps her amused with his stories the whole time. His kindness doesn't end there, either. Even though he's pretty quiet at home, Granddad Chet always compliments his daughter's cooking, and he stands up for the Baker family when Mr. Loski starts chucking insults their way.
On top of having a big kind heart, Granddad Chet is also one of the wisest blokes in this book—he's always got some sage words for Juli or some good advice for Bryce. In fact, we've got Granddad Chet to thank for Bryce's newfound open-mindedness when it comes to Juli. Do you remember what he tells Bryce when he gives him the newspaper article about Juli and the sycamore tree? Chet says that Bryce should read the article "without prejudice" (3.65). That advice isn't easy to take, but wise Granddad knows to give Bryce a little time.
So even though Bryce doesn't listen to him right away, over time Granddad's words sink in. And when Bryce realizes he's got a huge crush on Juli, Granddad Chet is right there to support his grandson. You might even say these two become the best of friends.