There's a nice scene where a depressed Heather hangs out with Zack in a garage. At first, he can't figure out why the little girl seems so sad, until he realizes that she's homesick. He completely drops his Jerkass Fašade and agrees to help her make a necklace to make her feel better.
And at the end of the movie, he's seen wearing the necklace! Aww.