The Spectacular Now
by Tim Tharp
Marcus starts dating Cassidy after she breaks up with Sutter. He's a really decent guy, who does all kinds of volunteer work because he's genuinely concerned with helping others. His version of confronting someone for seeing his girlfriend behind his back is to go talk calmly with Sutter and get advice from him about how to make Cassidy happier.
As you can guess, he's just a wee bit boring.