The dialogue that best helps develop both characters for readers is:
“I hope my uncle can get us tickets,” Sadie said. “I know I’m an optimist, but it could be really hard because the band is so popular.”
“Well, I’m usually skeptical and I still think we have a good chance,” Marco said.
This exchange effectively illustrates Sadie's optimistic nature and her hopefulness about securing tickets, while also highlighting Marco's more skeptical and pragmatic perspective. It shows their differing personalities and sets a foundation for their dynamic as friends.