We first meet David in Laurel's biology class, when she notices him watching her (not in a creepy way, don't worry). He introduces himself to her after class, saying that since she's new, he wants to welcome her to Crescent City. That's sweet, right? He's originally from L.A. so maybe he knows how it feels to be new to a place.
It helps that he's not a bad-looking dude, which Laurel notices right away: "His eyes caught her attention first. They were a bright blue that contrasted with the olive tone of his skin […] His slightly wavy, light-brown hair was on the longish side and slipped across his forehead in a soft arc" (1.14). And guess what? He also has a nice smile. Yup, this guy's a dream boat.
David's friend Chelsea finds him attractive, too, though David seems unconscious of his charm. Chelsea and Laurel happen to see David mowing the lawn shirtless one morning, and Chelsea comments, "'I think I've died and gone to heaven'" (4.32). And though it seems like David's handsome enough that he could be conceited about his looks, he isn't at all, and instead David's self-assured without being arrogant, though he comes close when the topic is science.
In David's defense, he is a wiz at biology, which helps him find an excuse to spend time with Laurel (since she's decidedly not a bio genius). And since he has a decent microscope at home, Laurel turns to him for help figuring out what the flower growing out of her back might be. Once Laurel confides in him about her situation, he comes up with biology-based explanations for her vegan diet, the fact that she doesn't really need to breathe, and so on.
What are we saying? Basically that if we had to compete in a biology quiz match for hot teenagers, we'd want David on our team.
David lives with his mom (his dad left a number of years ago), and as the man of the house, he has a lot of responsibilities. When Laurel first goes over to his house, she compliments it, calling it pretty. David responds: "'Should be […] I spent two weeks this summer painting it'" (3.62). Clearly he's pretty handy when it comes to household tasks.
He's also a pretty trustworthy dude. At first, he's the only person Laurel tells about the blossom on her back. He's willing to believe Laurel even though it sounds crazy, though he does ask her first whether it's a joke. Laurel realizes, though, that "It wasn't disbelief; it was uncertainty. He just didn't want to be the victim of a stupid prank" (6.67). Once he's on board with the whole thing, though, he is totally on Laurel's side, and he goes out of his way to be helpful and supportive.
Example: When Laurel is freaking out about being a faerie, David tells her that he'll be there for her no matter what she needs. He says:
Whatever you need, I'll be. If you need the science geek to give you answers from a textbook, I'm your guy; if you just want a friend to sit by you in bio and help you feel better when you're sad, I'm still your guy. (10.38)
He also offers to be more than a friend, and takes it gracefully when Laurel says a friend is all she needs right now.
David's even more supportive once he gets his driver's license, ferrying Laurel to and from the hospital where her dad stays when he becomes ill. David also shows up at the bookstore to help Laurel out during her shifts, and even more drastically, David agrees to drive Laurel to Barnes's place to see whether it looks sketchy before the land deal goes down (though getting arrested for trespassing is not high on his priority list).
No matter how crazy Laurel's life gets, David is there for her. She tries to apologize for getting him in over his head (literally—remember, the trolls tried to drown them), and he responds:
I knew what I was getting into when I signed up…Well, I guess I didn't know everything, but I knew you were different. From the first time I saw you, I knew there was something… something special about you. (24.83)
Aw, that's pretty sweet.
David is responsible, loyal, and totally into Laurel. He gets a little overprotective sometimes, such as telling Laurel "'You're lucky you didn't get hurt!'" (9.38) after she meets Tamani alone in the woods for the first time. But on the whole, he's got her back, and we feel like he'll continue to look out for Laurel.