Stay Golden
A lot of YA would have us believe that we're destined to spend our lives with the person we fall in love with at 16. This is certainly true for a surprising number of very happy couples I know. But, for most people, love arrives later, and sometimes doesn't stick around. People find themselves divorced, or broken up and entering the world of first kisses in all their giddy glory once more. And, though there are no more first loves, there are first second loves, or first third loves. Each relationship presents its own peril and promise, and its own learning curve. We also don't get to choose when we first experience great loss. It may happen at 15, but it's far more likely to hit in our twenties or thirties when parents start to show their age, or in our forties and fifties when our own bodies begin the business of loss and transition.
You're A Wizard, Harry!
So much of YA is about the discovery of latent potential. Though that's a powerful theme for a teenager struggling in an environment that misunderstands or devalues his or her gifts, it's both powerful and poignant for an older reader stuck in a bad job, or who may be pursuing a passion without making much headway. The hope of finding a calling and of having our talents fostered is not one that withers as we age. We may sacrifice that hope to the need to pay rent or take care of our kids, but the desire to have your abilities recognized and rewarded never goes away.
No One Goes Beyond The Wall
The stereotype of adulthood is that after a certain point, it becomes a rut deep enough to function as a trough. The moments of exposure to new experiences become more contained — a vacation, a new hobby, and also more controlled. They are things we choose instead of situations that are foisted upon us. We settle into a place, we build our routines, our social circles stay fairly static. But for this very reason, a kind of butterfly effect comes into play: We are tethered more tightly to each phase we occupy so that even small changes have deeply felt repercussions. The addition of a new girlfriend or husband to your peer group alters social dynamics. A change of address — even within the same city — means a new school district, new commute, new dry cleaner, new market. As we grow older, we may seek novelty ("We're going to Bali!" "I've taken up fire-dancing!" "I'm making my own jam!"), but real change is felt with great force, something echoed in the personal upheaval and literal revolutions of Young-Adult fiction.
Faction Before Blood
Whether it's at Hogwarts or Camp Half Blood, at the New York Institute, or in your chosen faction, the search for one's tribe is a major force at play in much YA. You will be tested, initiated, and branded with the symbols of your new clan, and in it you may find true acceptance, or you may once again need to set out on your own.