Who is Corinna from Dreamland and what is their importance?

Corinna is Dave's girlfriend. She meets Caitlin when Rogerson comes to her house to sell Dave marijuana. As a result, the two girls become friends even though they have little in common. Caitlin is able to be herself with Corinna, and she notes that it is one of the few times she can be herself without feeling like she's letting someone down. Corinna optimistically dreams of a better life, and when she realizes that Dave doesn't have that same aspiration, she leaves him.