InTo Kill a Mockingbird, Scout and Jem are brother and sister. Jem is four years older. Scout looks up to Jem but they also fight, as brothers and sisters do, and their relationship is sometimes competitive. However, Jem is generally encouraging with Scout, although as he gets older and enters adolescence, he feels the need to behave more like a man and wants the tomboy Scout to behave more like a lady. This is just a reaction in attempts to fit in to social roles in Maycomb which, as both Jem and Scout realize, is fraught with stubborn social traditions, residual racism, and legacies of family history.
Both Jem and Scout have the benefit of Atticus' and Calpurnia's guidance. Therefore, it is likely that they look at their world with more open minds than other children their age. Jem understands things a bit more than Scout on account of his age. Jem is also more emotionally affected by events in the novel because of this. Scout is still just as open-minded and innocent. Jem and Scout also share revelations as they mature. For instance, in Chapter 23, Scout and Jem share their thoughts on why Maycomb's society is the way it is. Scout concludes:
No, everybody's gotta learn, nobody's born knowin'. That Walter's as smart as he can be, he just gets held back sometimes because he has to stay out and help his daddy. Nothin's wrong with him. Naw, Jem, I think there's just one kind of folks. Folks.
And because she does look up to Jem, Scout spends a lot of time trying to see the world through Jem's eyes as well as her own. To this last quote, Jem replies:
If there's just one kind of folks, why can't they get along with each other? If they're alike, why do they go out of their way to despise each other? Scout, I think I'm beginning to understand something. I think I'm beginning to understand why Boo Radley's stayed shut up in the house all this time . . . it's because he wants to stay inside.
Despite Jem's need for independence as he matures, and Scout's stubborn innocence, they are very close. Their relationship is indicative of this and when Jem defends Scout from Bob Ewell, he shows himself to be a sibling and a protector.
Besides being brother and sister, Jem and Scout are also best friends, playmates, confidantes, and partners in crime. Aside from Dill, who becomes both Scout's "permanent fiance" and Jem's best pal during his stay with his Aunt Rachel each summer, neither of the children have any close friends. The tomboyish Scout has no girlfriends, and instead of playing with dolls, she sticks close to Jem and shares his outside interests. Likewise, Jem has no close male friends, and he usually includes Scout on his imaginative adventures, especially those concerning Boo Radley. They both share a love of reading, and they defend each other when necessary. Scout strikes out at one of the lynch mob when he manhandles Jem:
I kicked the man swiftly... I intended to kick his shin, but aimed too high. (Chapter 15)
while Jem comes to Scout's rescue on the trail home from the Halloween pageant when they are attacked by Bob Ewell. The two begin to grow apart as Jem grows older, but they remain close even into adulthood, arguing about past events and, being "far too old to settle an argument with a fist-fight," consulting Atticus together when necessary.