Everything I Need to Know I Learned from Harriet the Spy - Xander
Xander hasn't let on that he reads much since grade school, when it led to regular thumpings from Larry. Well, lots of things led to regular thumpings, but the reading thing was one he could actually control. So he did it on the sly, but he did it. He got his books from the main library in town, not the school library, as soon as he was old enough to walk there by himself.
He's read a lot of Heinlein, mostly the juvies, but some of the others too. Starship Troopers dozens of times, maybe. One of these days during a battle, he swears he's going to shout, Bugs, Mr. Rico! Millions of 'em! And I'm a-burning 'em down! And no one will have the faintest idea what he's yammering about. But it'll amuse him (if he lives).
If he ever had to pick just one book that meant something to him, it would be Harriet the Spy. The life of a girl in New York City -- he might as well have been reading about a girl from Mars (which he's done too, thanks to Heinlein). He imagines what it would be like, having a cook make all your meals (a definite improvement). Being raised, more or less, by a nanny, with your parents making a guest appearance in the occasional Very Special Episode. Not even Cordelia was raised that way.
Harriet taught him that friends could be angry with each other -- deeply, never-want-to-speak-to-you angry, and it still didn't have to be the end of the world, or the friendship. (Now, of course, he has different standards for "the end of the world," as in actual ruptures in the fabric of the universe and all.) It taught him you could be friends with girls in the first place (though that turned out to be another cause for thumpings from Larry).
He had this crazy realization just after Buffy came back from the big runaway summer. It was a crazy time anyway -- overwhelming relief, suddenly washed away by a tidal wave of anger. But right before that part hit, he realized he and Willow and Buffy -- they were like Sport and Janie and Harriet. Just like all the times he'd imagined himself in that part of Harriet's world.
That's when he knew it would be okay to let the anger in. It would come, and then it would go, and their friendship would still be standing.