I'm not really sure how to answer this, but I'll throw out a thought that might be relevant:

I think this depends somewhat on the maturity level of the YF in question. But for me, I always try to respect and honor my YF by treating him as an adult. I try to regard him as a friend and an equal, but I never talk down to him or "lower myself to his level" by behaving like a teenager. I expect him to act with maturity in his friendship with me and, hopefully, in doing so, he will be inspired to "rise above" childish ways and grow to become the Godly young man I so desire him to be.

Of course, he is still a teenager, and I want to make sure I remember that and give him a lot of grace ... but I think by always treating him as "better" than he sees himself, it gives him something to aspire to.

Blessings,
Rainboy