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 showcases Sadie's optimistic personality as she expresses excitement and hope for the event, while Marco's response highlights his brooding nature and skepticism. It effectively contrasts their outlooks, providing insight into their individual characters while driving the scene forward.