When my husband and I contemplated having a child in our home, we naturally contemplated having a little copy of ourselves. Studious, quiet, intuitive, caring, introverted. Therefore, we did not ever imagine a weekly dungeons and dragon game in our dining room, with its raucous mix of personalities, gluttony, dice, and fantasy. But because nobody is a copy of anybody, our studious, quiet, intuitive, caring, introverted son is also a dedicated Game Master. His game has been going on for five years now with more or less the same crew, and shows every likelihood of going on until three of its four permanent players go off to college in (gulp!) two and a half years. His first game lead to a second; A couple of times a month, he and his girlfriend play with a group of adults from church, and what a gift that has been! Their affectionate guidance has mentored his adolescence in ways that parents just can't do.
D&D taught our introverted child to make phone calls, to organize activities, to be a leader, to deal with different personalities. The young people in his group have squabbled like the siblings that none of them have, but the game (almost always, especially in the last couple of years) goes on. We no longer hover in expectation of tears or tyranny; they've all matured nicely, and their game has smoothed out accordingly. I credit D&D with a lot of growth for my kid...it's been worth every spilled coke and every plate of cookies.