The last page of Perfect contains only the words, "a perfect paper airplane" (57.17). Tony and Vanessa give the airplane to Cara at Conner's funeral. They were with Conner on the Aspen Springs wilderness retreat, and at the end of the retreat, each kid got a letter from his or her parents. Conner's parents wrote to him about staying on track with his coursework so he could go to college on time.
What, you were looking for something like "we care about your mental health"? Surely you jest. That's just not how the Sykes parents roll.
The letter was the last straw in the parental-pressure saga for Conner, who folded the letter into an airplane and let it fly before jumping off a cliff. He may have fallen under his parents' unyielding expectations, but the book ends with what might be understood as a reminder to make your own perfect and fly.