The dialogue that best helps develop both characters for readers is:
“‘No way!’ Sadie beamed. ‘Clear your schedule. We’re going to have a blast.’
‘I don’t know,’ Marco said slowly. ‘Are you sure we’ll even get tickets? This is going to be a pretty big deal.’
‘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 response effectively showcases Sadie's optimistic nature and excitement about the event while contrasting it with Marco's skepticism and tendency to focus on potential negatives. It gives insight into their personalities and the dynamic of their friendship.