We're considering giving Chelsea an award: Blunt Conversationalist of the Year. When she first meets Laurel, she grills her about her vegan diet. David is used to it, and he sort of apologizes to Laurel on her behalf:
Is it Chelsea? She didn't mean to make you self-conscious about your lunch; she's just really honest all the time. It's actually kinda of refreshing once you get used to it. (2.34)
She's actually pretty sweet, too; one time when she and Laurel hang out, she brings organic strawberries just for Laurel to eat.
It turns out that Chelsea is a fan of faeries—well, the version of faeries that humans have in their stories. She tells Laurel: "I love faeries! […] I went through this phase about a year ago where everything I did had something to do with faeries. I have like, ten books all about faerie and pictures on my ceilings" (11.114). Man, wouldn't Chelsea be surprised to learn that Laurel actually is a faerie?
In addition to being a marathon talker, Chelsea is a cross-country runner. We know this because Laurel runs into Chelsea early one Saturday morning, while Laurel is walking to David's place and Chelsea's running by. When Laurel tells Chelsea what her destination is, she laughs and says: "Well, welcome to the David Lawson fan club. I'm already president, but you can be treasurer" (4.25), so we'll go ahead and add good-humored to her list of traits while we're at it.
Chelsea figures out that even though she's into David, he doesn't return her feelings, but this doesn't stop her from being a good friend to both him and Laurel.