Why did the author introduce Boo at the end of chapter 14?

The main idea in Chapter Fourteen is Dill's escape (running away) from home, and his need for a family..... people who care about him. This episode leads Scout to muse about why Boo doesn't simply run away, that possibly running away from Maycomb would solve his problems of isolation...... that maybe he'd find a family of his own. Dill, as young as he is, points out that unlike himself, Boo hasn't a destination to run to.