I'm no expert in Adolescent development, in fact if you're an expert psychologist I welcome your critiques. But these are just some observations I have made in my few years of youth ministry experience.
If you decide to invest in a teenager, you'd better be ready to invest it all. You are dealing with a delicate, fully rational, and very real human being who is waiting (or perhaps has given up on waiting) for some adult to show them that they can be trusted. Now, there is a real misunderstanding between adults (and adult institutions ((even the church))) and adolescents. Adults are generally afraid of adolescents, let's just be honest. We think they are harsh, callous, disinterested in us, sometimes mean, and just disrespectful. Adolescents think adults are distant, untrustworthy, abandoning, and thoroughly against them. Here is an example of how this mutual misunderstanding is made manifest and is perpetuated:
Step 1: Adult decides to show interest in adolescent. She or he decides to give them the benefit of the doubt, to trust them and to start to build a relationship with them.
Step 2: Adolescent is curious about the interest shown in them and starts to examine and even build trust in the adult.
Step 3: Adolescent, either unprompted or out of some break of trust, lashes out (perhaps continuously through a period of time). They lie, cuss, shut-off, or say something hurtful--perhaps something ungrateful for the "charity" shown them by the adult.
Step 4: Adult decides their investment was too much. It is too hurtful and they're being disrespected. Time to give up. Adult reasons that it was worth a shot but the adolescent just didn't want their investment. So they leave, either physically or relationally, and retreat back into their more adult systems of relationship.
Step 5: Adult believes adolescent to be harsh and callous, Adolescent believes they have been abandoned once again and that their best hope if to create higher and thicker defensive walls and to retreat back to their own "safe" relationships.
Thus, the misunderstanding has been further solidified.
This scenario, though it may sound far fetched to some adults and/or adolescents, is far too familiar. I've seen it played out in one way or another too many times. It happens among parents, among teachers, among youth-workers, among all sorts of well-meaning adults. And, although there are of course some exceptions to every rule, adolescents have built up defense mechanisms and relationship clusters to protect them from their shared sense of abandonment.
But the truth is that adolescents need and actually want to trust adults. They need to be loved as children and respected as adults but they need someone who's willing to tread through their junk long enough to meet that need and to fulfill that desire. They desperately need adults who are willing to make the whole investment and to make it past Step 3 with the resilience to prove that they can be trusted and that they won't abandon.
When adolescents lash out, when they say mean things, when they hurt others they are reflecting their own hurt. They are giving us a sign of just how difficult times are for them and how much they need someone to understand. They need someone who will walk with them through the tough times and show them that there's something on the other side. They need to be loved unconditionally. They need investors who aren't looking for immediate profit but are willing to patiently struggle toward delayed gratification. They need adults who can make it past Step 3 without running away screaming.
So if you're not willing to go the distance, if you're not willing to suffer with (and because of) adolescents, then don't make the investment. Sure, show kindness whenever the opportunity arises, but don't tease them. But if you will suffer with them and you will take what they can dish-out because you know that resurrection is on the other side, then do it. They need you. Don't give up on them and don't give in to the cynicism that says they're just harsh and callous. Love and invest beyond Step 3 with humility and grace.