What part do Scout's comments and reactions play in spurring Jem to accept Dill's dare?
Jem accepts Dill's dare to touch the Radley house in the first chapter of Harper Lee's novel, To Kill a Mockingbird. Jem considered the dare for three days before screwing up his courage. According to Scout, "Jem had never declined a dare." Jem declared that he'd never been afraid of passing the Radley house before. But Scout added,
"Always runnin'," I said.
Worried that Boo might kill or eat him if he caught him, Jem told Dill that he had his sister to think of.
... When he said that, I knew he was afraid. Dill had his little sister the time I dared him to jump off the house... Then he jumped, landed unhurt.
Dill prodded Jem further by telling him if Boo appeared, he and Scout would hold him to down until Jem got away. Jem still had some thinking to do, and he didn't make his decision until Scout made one last non-verbal comment.
Then I sneered at him.
That did it.
Jem threw open the gate and sped to the side of the house, slapped it with his palm, and ran past us, not waiting to see if his foray was successful.
In the end, Jem couldn't face the prospect of declining the dare AND facing the possible taunts of his little sister.