don't. move. a hand -- slimy and scabbed -- a hand of death -- grips the half-open compartment door, pushes it aside. reveals: a towering, cloaked figure, its face hidden beneath its black hood. crookshanks' hair rises and as she hisses.  whooshhhhh. the folds of the hood tremble. a chill, rattling intake of air is heard. the flames in lupin's hands sputter. a sound swells in harry's ears. eerie. painful. the sound of a woman screaming. harry's eyes roll up, eyelids fluttering. and then.  a silvery white light drifts from his mouth. the world spins off its axis and harry falls.  glasses tumbling hard to the ground.  then harry.  the muscles of his jaw twitching. thunder cracks. lightning paints the icy windows.
chocolate. eat. it'll help.
a dementor. one of the guards of azkaban. it's gone now. harry frowns in confusion.
i need to have a word with the driver. excuse me. eat. it'll help. as he leaves, harry turns to ron and hermione.
intriguing, yes? would anyone like to venture a guess as to what's inside?
very good, mr. finnigan. can anyone tell us what a boggart looks like?
terrifying, yes. luckily, a very simple charm exists to repel a boggart. let's practice it now, shall we? without wands, please.  riddikulus!
good. so much for the easy part. you see, the incantation alone is not enough. what really finishes a boggart off is.  laughter. you need to force it to assume a shape you find truly amusing. neville, come up here, will you? neville eyes the rattling wardrobe, steps forward queasily.
what would you say is the thing that frightens you most?
didn't catch that, neville, sorry.
hmmm.  yes. neville, i believe you live with your grandmother?
it won't. but i want you to picture her clothes, only her clothes, very clearly in your mind. can you do that?
that's fine. we don't need to hear it. if you see it, we will. now, when i open this wardrobe, neville, here's what i want you to do.  lupin leans close to neville, whispers. neville's eyes pop open in shock. consider lupin uncertainly.
you can do this, neville. neville nods nervously, takes a deep breath.
right then. wand at the ready. one. two. three! sparks jet from lupin's wand, strike the doorknob, and the wardrobe bursts open. instantly, snape appears, eyes flashing hideously as he stalks forward. neville backs away in fright.
think, neville. think!
ron! forward! snape dissolves into a mad whirling mass, then mutates into a.  giant spider. as ron gasps, harry and hermione exchange an uncertain glance. lupin puts his hands on ron's shoulders to steady him. ron raises his wand.
parvati! as parvati steps up, the spider spins faster and faster, a dizzying blur, then reappears as a vampire.
mr. thomas! as dean steps up, the vampire's undulating body attenuates, its skin darkening with diamond-thatched scales becoming.  a giant cobra.
next! .  turns, sees harry step forward expectantly. concern flickers through lupin's face. the jack-in-the-box pivots on its spring, its face tumbling toward harry, becoming more sinister, transforming into a.
here! crack! -- the dementor vanishes and a roiling mist appears, which becomes clouds. something glows within the clouds, white, silvery and round.
riddikulus! pop! the orb deflates like a punctured balloon, whizzes crazily about the room, then darts back into the wardrobe. the door slams shut and the class cheers.
well done, everyone. i think that's enough excitement for today. as the students exit, chattering loudly, only harry, subdued, remains behind. at the doorway, lupin glances back, exchanges a private glance with him. as he exits, the wardrobe gives one last rattle.
so. no hogsmeade, eh ?
well, don't feel too bad. i was roundly disappointed the first time i went.
no. i was just trying to make you feel better. honeydukes' sweets are the best in the world. their pepper imps are so strong you smoke at the ears. and zonko's joke shop may be dangerous, but you can't beat their stink pellets.
yes, that too.
you'd like to know why i stopped you from facing the boggart. i should think it'd be obvious. i assumed the boggart would take the shape of lord voldemort. harry frowns. lupin studies him curiously.
but clearly.  i was wrong.
well, well. i'm impressed. that suggests that what you fear most of all is.  fear. very wise.
dementors force us to relive the worst memories of our lives. our pain becomes their power.
the first time i saw you, harry, i recognized you immediately. not by your scar. by your eyes. they're your mother lily's. yes. i knew her. she was there for me at a time when no one else was. we used to talk for hours. she was not only a singularly gifted witch but an uncommonly kind woman. she had a way of seeing the beauty in whoever she met, even -- and perhaps most especially -- when that person couldn't see it in themselves.  lupin's eyes glaze in memory, then he blinks, smiles.
which perhaps explains her affection for your father. james had, shall we say, a certain talent for trouble. a gift, rumor has it, he passed on to you. lupin turns, eyes harry affectionately. harry smiles vaguely.
i could tell you stories -- and there are many about your parents, harry -- but know this.  they lived. every moment of every day. you should know that. that's how they'd want to be remembered.
i'm sorry about your broom, harry. there's no chance of fixing it?
dementors are among the foulest creatures that walk this earth. they feed on every good feeling, every happy memory, until a person is left with nothing but his worst experiences. you're not weak, harry. the dementors affect you most, because there are true horrors in your past. horrors your classmates can scarcely imagine. you have nothing to be ashamed of.
i'd consider you a fool if you weren't.
there was only one that night.
i don't pretend to be an expert, harry. but yes, i can teach you. perhaps after the holiday. for now, though, i need to rest. i'm feeling.  tired. harry turns, studies lupin's haggard face. a weary smile appears as hedwig's reflection glides over lupin's irises.
beautiful.  harry looks up, watches hedwig pinwheel through the blue, past the clock tower and exit frame. camera holds, the skies pales, and snow begins to fall. we tilt down.
you're sure about this, harry? this is very advanced magic. well beyond ordinary wizarding level.
very well. the spell i'm going to teach you is called the patronus charm. ever hear of it? harry shakes his head.
a patronus is a kind of positive force. for the wizard who can conjure one, the patronus works something like a shield. the dementor feeds on it instead of him. just then, the trunk rattles violently. as harry's eyes wander, lupin snaps his fingers, brings his attention back.
but in order for it to work, you must think of a memory. and not just any. this memory needs to be a very happy one. and powerful. harry thinks a bit. then.  nods.
got something? good. let it fill you up. lose yourself in it. then speak the incantation: expecto patronum. without your wand.
right then. shall we? harry nods, raises his wand. lupin, watching closely, reaches over, grips the lid of the trunk.
concentrate, harry. concentrate.  as lupin flings open the case, harry opens his eyes. in the sun's blood-light, the dementor looks particularly horrific.
here! crack! -- the dementor mutates into a silvery white orb.
riddikulus! lupin flicks his wand, sends the orb back into the packing case. harry stands blinking. dazed. lupin fishes a chocolate frog from his pocket. presses it into harry's trembling hand.
quickly. harry studies the frog. takes a bite. begins to recover.
boggart, harry. the real thing would be much, much worse. just out of interest, what were you thinking of? what memory did you choose?
that's not good enough, harry. not nearly. harry glances toward the window, at the bloody sun.
is it strong? harry looks up into lupin's eyes. emotional. nods.
then let's try it. harry takes a breath. tosses the frog aside. poises himself.
think, harry, think --
riddikulus! crack! the dementor vanishes. harry's arm drops. slack. lupin eyes harry with a kind of awe. his voice barely a whisper.
well done.
so you know, harry: you'd have given your father a run for his money. and, believe me, that's saying something. harry ponders this. then speaks, deep inside himself.
professor? snape turns. sees lupin standing in the shadows.
harry? you all right?
i seriously doubt that, severus. it looks to me as if it merely insults anyone who tries to read it. i suspect it's a zonko product. nevertheless, i shall pursue any hidden qualities it may possess. as you say, it's my area of expertise. come, harry.
i don't know how this map came to be in your possession, harry, but i'm astounded that you didn't turn it in. did you ever stop to think that this -- in the hands of sirius black -- is a map to you? harry walks silently. lupin can barely contain his anger.
your father didn't set much store by rules either. but he and your mother did give their lives to save yours. gambling their sacrifice by walking about the castle unprotected, with a killer on the loose, strikes me as a poor way to repay them. i won't cover up for you again, harry. lupin enters his office, tosses the map on his desk, and begins to sort through some papers. harry lingers briefly in the doorway, absently eyes the waxing moon that glimmers beyond the window, then starts to turn away. stops.
and who was that, harry?
very well. i'd like you to return to your dormitory now. oh, and harry? don't take any detours. as harry looks back, lupin taps the map.
if you do. i'll know.
looking a bit ragged, aren't we, sirius? finally the skin reflects the madness within.
how long have you known?
you're the brightest witch of your age i've ever met, hermione.
wait, sirius --
all right then. as you wish.
harry! you've got to listen --
someone else betrayed your parents, harry. someone in this room right now. someone who, until quite recently, i believed to be dead.
severus --
don't be a fool, severus!
quiet, sirius!
pettigrew. he was at school with us. we thought he was a friend.
i thought so, too. until you mentioned seeing pettigrew on the map.
we would.
harry, this man.
hello, harry. harry jumps. lupin turns, smiles through haggard eyes.
saw you coming. the marauder's map lies open on an otherwise bare desk. harry nods, looks back to lupin. unable to disguise his shock at lupin's appearance.
i've looked worse, believe me. harry eyes the open desk drawers.  the bare bookshelves.
resigned, actually.
it seems that someone has let slip the nature of my condition.
whoever. it was bound to get out. this time tomorrow, the owls will start arriving. parents will not want a -- someone like me -- teaching their children.
has already risked enough on my behalf. besides, people like me, well.  let's just say i'm used to this by now. but before i go, tell me about your patrons.
a stag.
your father used to transform into one. that's how he was able to keep me company when i became.  sick. he was a great friend james. lupin smiles wanly, lifts his sorry suitcase. then stops.
there are stories about him and your mother, you know. some are even true. but i think it's safe to say, in the end, you'll know them best by getting to know yourself. lupin then -- with a wicked twinkle -- raises his wand.
mischief managed. harry watches the map go blank. looks back. lupin is gone.