My nephew turn 14 next week. We are very close, we spent a lot of time together when she was a child, because my sister worked a lot and she spent years at my parent's house. I don't have a child yet, but I think that what a feel for her must be very close to what a mother feel for a child.
Beside she looks so much like me, both emotionally and physically. Most of time I know exactly what she thinks, what she's passing through, because I felt the same. Now that she is a teenager things have changed in some way: I see her growing, searching for herself, and it's an honor and a pure joy to experience alongside her. It's also a challenge to find new ways to stay by her side..the times in which all she needed was a hug and some tickling to make her laught are almost gone, the problems that she face now are so intimate and personal that some time I ask myself "what shoul I do for her?". Having walked the same path is so strong the tentation to show her the way.
But most of times I discovered that the best solution is to step back, as difficult as it is, and let her be herself and make her choise, giving some advice only if requested, and let her find her own way.
Watching her grown is such a gift.