David is a brainiac and one of the few people who treats Melinda decently. He's in Melinda's social studies class and is her lab partner in biology. It's not clear how much David suspects about Melinda's problems, but it seems likely he's aware things aren't right with her. His protectiveness toward her, his gentle but strong urgings that she speak her mind – these suggest he really cares about her.
David also helps us understand how Melinda is feeling about dating and guys in general. When he invites Melinda to join him and his dad for pizza after a football game, she refuses. Melinda is literally of two minds on what seems like a pretty basic decision:
Melinda One: "Get a life. It's just pizza. He wasn't going to try anything. His parents were going to be there. You worry too much. You're never going to let us have any fun, are you? […]" (62.12)
Melinda Two: "The world is a dangerous place. You don't know what would have happened. What if he was just saying his parents were going to be there?" (62.14)
Whoa! We thought Melinda trusted and liked David. But Melinda's conflicted feelings make more sense when we learn Melinda's secret. The memory is so painful for her that she bites through her lip and needs stitches. Melinda seems to realize on some level that if she's ever going to be able to trust guys again, she'll have to face her fear, painful as it may be.