Symbolism, Imagery, Allegory
If you want a paper airplane to glide rather than nose-dive, it has to be symmetrical. In other words, in order to keep it balanced, the folds have to be perfect.
The last four words of Perfect are "[…] a perfect paper airplane" (57.17). We don't see the airplane or know of its existence until the last page. When Tony hands it to Cara at Conner's funeral, he says, "Vanessa and I found this, out in/the desert. I think it drove him over" (57.16). Wait, wait, wait… Say what?
It's not just any paper airplane, Shmoopers—it's the last letter Conner received from his mother. Here's an excerpt:
All you have to do is maintain
your GPA and, of course, score
well on your entrance exams.
Not really much more to say
except to let you know Cara
has already been accepted
at Stanford. You can do as well.
After all, you're her twin. Mom. (44.44-45)
Not only does she compare a suicidal kid to his sister, she doesn't even include a cursory love you or anything like that before the she signs off. It's no surprise that Conner, who has recently stopped taking his meds, is too unstable and exhausted to keep trying to live up to her standards. He's done been sick of his parents' push for perfection, and the insensitivity of this note is the last straw—he's done trying.
Before he jumps, though, Conner sends one final, perfect object over the cliff. It's the paper airplane, a beacon to go before him, something that can fly, even as he falls.