Have you ever noticed how every hero has a cool partner? Batman has Robin, and together they're an unstoppable team. Imagine if, in the middle of a mission, Robin started fighting with Batman, popped the Batmobile's tires, and hid his stuff? They'd lose!
The Bible says the people who live in our house are our team. And we have to "do good and never harm, every day." If you keep fighting, breaking your brother's toy, or saying mean words, you're acting like "villains" on your own team!
But when one sibling helps another make the bed, or shares candy with each other, you become the Justice League! Our Father in Heaven loves seeing siblings take care of each other.