What are some quotes that show that Jem is a protective brother in To Kill a Mockingbird?

In Chapter 4, Scout is passing the Radley yard when she notices something shiny coming from the knothole in one of the trees. Scout ends up finding a stick of Wrigley's Double-Mint gum and begins chewing on it. When Jem comes home and asks Scout where she got the gum, Scout tells her brother that she found it in one of the Radley trees. Jem demonstrates his protective nature by saying,

"Spit it out right now!" (Lee 22).

Jem proceeds to yell at Scout for her "dangerous" stunt and tells her that she could have died. Another scene that displays Jem's protective nature and concern for Scout's well-being takes place in Chapter 14. Immediately after Scout and Jem get into a fight, Scout knocks on Jem's door to ask him if he can take a look underneath her bed. Jem does not hesitate to come to Scout's aid, and he goes to the kitchen to grab a broom. Lee writes,

"Jem made a tentative swipe underneath the bed. I looked over the foot to see if a snake would come out. None did. Jem made a deeper swipe" (Lee 86).

Fortunately, there is no snake underneath the bed and Dill Harris surprisingly comes out from his hiding spot.

Jem shows that he is a protective brother on Scout's first day of school. Scout is offended when Miss Caroline tells her to instruct Atticus to stop teaching her to read, and Jem responds, “Don’t worry, Scout...Our teacher says Miss Caroline’s introducing a new way of teaching" (page 17). Jem mistakenly calls this new method of instruction the Dewey Decimal System, but he is trying to reassure Scout about Miss Caroline's strange methods of teaching and to be comforting on Scout's first day of school. Later, in Chapter 4, Jem pushes Scout in a tire until she stops right in front of the Radleys' house, which they fear. Jem, out of ignorance about the Radleys but also out of a sense of protection, yells at Scout to run away as quickly as she can from the Radleys' place. He clearly cares about her safety.
At the very end of the book, Jem is also protective towards Scout when she fails to come in on cue during the Halloween pageant. Jem reassures Scout about her performance, and Scout thinks, "Jem was becoming almost as good as Atticus at making you feel right when things went wrong" (page 262). Jem also waits for Scout backstage until everyone else goes home so that Scout can be spared seeing anyone in the audience; that is why they head home alone and fall prey to Bob Ewell.