Why does Rusty-James ask Motorcycle Boy to stay home until their father gets back?

Rusty-James asks Motorcycle Boy to stay home until their father arrives because he's worried that otherwise he'll pass out from his wounds alone.
Before Rusty-James goes home, he gets into a fight and is stabbed. He worries on the drive that he'll keel over in the street and thinks that Motorcycle Boy might be at home so it's better that he goes there. When he arrives, his brother is there. He doesn't respond to Rusty-James's question about food and Rusty-James notes that Motorcycle Boy has poor hearing and is colorblind.
After he gets food, Rusty-James washes the knife cut and then goes back out to Motorcycle Boy. He asks him to stay until their father gets home. This time, Motorcycle Boy acknowledges him. S. E. Hinton writes:

"Poor kid," he says to me, "looks like you're messed up all the time, one way or another."

Rusty-James is surprised that his brother is worried about him. Soon after, their father arrives.