Jem is a good big brother who looks after and takes care of his little sister. It is interesting though, that over the course of the book, which encompasses about two years, Jem goes from telling Scout basically to stop being a girl to telling her to act like one. The following passage is when she challenges Jem to go back to the Radley house to get the tire she had left there:
"I swear, Scout, sometimes you act so much like a girl it's mortifyin'" (38).
Then, after Aunt Alexandra has come to stay with the Atticus and the kids to help them with their upbringing. Scout doesn't agree with her aunt and doesn't like her much, either. Jem counsels her by saying,
"You know she's not used to girls, . . . least ways not girls like you. She's trying to make you a lady. Can't you take up sewin' or something'?" (225).
Jem's growth in maturity is easily seen between these two comments that he makes to his sister. It also shows how his perception of her changes throughout the book. He starts to understand that she should be learning to act like his aunt and not like him and the other boys.
At other times, Jem takes care of Scout without question and even tells her not to worry. During the night when Miss Maudie's house burns down, Jem is told to watch her, so he stands with her next to the Radley house watching the fire. He notices that Scout is really worried and he says the following:
"Don't worry, Scout, it ain't time to worry yet, . . . Looka yonder" (70).
Jem goes on to teach Scout that she will know when to worry by the actions of her father. At the fire, Atticus had his hands in his pockets and remained calm. Whenever Jem got scared, he looked to see how his father was acting and was able to calm down and not worry. This scene shows Jem both mature and loving towards his sister. Sure, they get in fights and arguments like siblings do, but for the most part, Jem is a good, mature and loving brother.