The dialogue that best helps develop both characters for readers is:
“We’re going to have so much fun,” Sadie said. “I bet we’ll get to meet the band. I bet we’ll even get to hang out with them!”
“We probably won’t even get to go,” Marco said. “I bet the whole show will get canceled and we’ll have a terrible day.”
This exchange effectively highlights Sadie's optimistic nature as she excitedly imagines the fun they will have and her belief in positive outcomes. Conversely, Marco's response captures his skeptical demeanor, focusing on the negative possibilities and expressing doubt about the plan. Their contrasting viewpoints are clearly demonstrated, providing a deeper understanding of their characters.