Craig is Sam's "cut and hunky" (2.2.11) boyfriend. He's in college, an artist, a male model (for JCPenney, but still), and he buys alcoholic beverages for his underage friends. Swoon, right? Well, we left out the part about him being a dirty cheater. What do you think now?
Throughout the book, Craig is conspicuously absent a number of times. He doesn't show up at Rocky Horror, forcing Charlie to play the part of Rocky (not that Charlie minds). He's "too busy" (3.7.8) to go with Sam to the Sadie Hawkins dance. We're not sure if Sam has any suspicions about Craig's absences, but… come on.
After much cajoling by Peter, Craig finally tells Sam about his infidelities. He takes full responsibility for his actions and "was nice enough to tell her that she was right to break up with him. And that she was a special person" (4.14.4).
Let's sidebar on Peter for a moment. Peter encourages Craig to tell Sam that he's cheating on her, "because she wasn't just some dumb high school girl" (4.12.12). By that logic, we guess if Sam were a dumb high-school girl, it would be okay to cheat on her? Hear that sloshy, bubbling noise? That's the sound of our opinion of Peter going down the drain.
Anyway, back to Craig. He does do one major good deed: he encourages Charlie to be a deejay. We hope Charlie will take his advice to heart.