If you liked 'Carpe Diem' you may well enjoy my new James/Lily short story, 'We Walked this Way Once'.

As ever, JKR's characters and world.

Go on… leave a review! A Patronus and a Promise

"Till the sun grows cold,

And the stars are old,

And the leaves of the Judgement Book unfold."

Bayard Taylor: "Bedouin Song"

Heading down the sun-streaked corridor with Ron and Hermione, to the final lesson of the day, Harry felt particularly cheerful. School had reverted life to a mundanely reassuring pace, the terrors of the holidays seeming somehow to fade amongst the gossiping portraits, and clanking suits of armour that lined the corridors. The challenges of the work expected of them that year were immense, bags sagging under the weight of heavy text books as they struggled from lesson to lesson. Homework seemed to change into a life form of its own, breeding silently when they weren't looking, multiplying simple pieces of research into horrifying monsters to be wrestled into submission each night.

As ever, once at Hogwarts, they seemed to be oddly isolated from the real world, only Hermione's copies of the Daily Prophet and anxious letters from various members of the Weasley family informing them of the situation beyond the castle walls. Harry was surprised to discover that some days were so normal that when he glanced up at Ginny over his homework, he felt a jolt in his stomach as he suddenly remembered they were to be married in a matter of weeks. It still didn't seem real sometimes.

The corridor was cluttered with black-robed students jostling as they headed in various directions, and Harry caught a fleeting glimpse of familiar bright red hair bounding upwards towards Muggle Studies, before they turned the corner, passed through a tapestry concealed doorway, and clattered down a flight of rickety narrow stairs for their Defence Against the Dark Arts lesson.

"I still think it's weird having him teaching us," Ron grumbled to Harry as they neared the bottom of the stairs.

"I can't see why," Hermione retorted, adjusting the weight of her bag on her shoulder. "I know he used to teach Transfiguration, but don't forget, he's been involved in defending us from the Dark Arts most of his life. It tells you all about it in 'Hogwarts: A History'. You really should read it Ron."

"And we all know that Dumbledore is particularly famous for his defeat of the dark wizard Grindlewald in 1945," Harry added, causing Ron to look at him in astonishment. "Chocolate frog collector's card," Harry admitted sheepishly.

They came to a halt in the corridor outside the classroom and leaned patiently against the wall with the rest of the class, waiting for Dumbledore to arrive.

"I suppose it makes a lot of sense him wanting to teach us the Dark Arts stuff himself," Ron commented, dropping his bag on the floor with a thud. "After some of the teachers we've had in the past few years, and what's going on out there now, I suppose he doesn't want to take any more risks."

"Wonder what he's got for us today," Hermione said eagerly, glancing impatiently at the arched oak door, clearly wondering where the Headmaster was.

"Could be anything," Harry replied, shrugging his shoulders. "I hope we get out quickly though; I want to see Ginny for a while before Quidditch practise tonight."

"Not a chance," Ron laughed suddenly. "She's got that detention with Professor Flitwick tonight, don't you remember?"

"Now which detention is that one?" Harry groaned, mentally working his way through the various punishments Ginny had acquired since the start of term. "Was that the cushion that turned into a chicken that they couldn't catch? Or was it the parchment that spontaneously self-combusts when you try to write on it and almost burned through the desk?"

"Neither," Ron chuckled. "She's still got the parchment detention to do with McGonagall on Friday. The Flitwick one was the shrinking dust she put on his stack of books."

"It's not funny," Hermione said crossly, as Ron and Harry collapsed into fits of laughter at the mental image of tiny Professor Flitwick gradually sinking towards the floor and disappearing from view behind his desk. "Anything could have happened."

"At this rate she's going to need a booking system for her detentions," Harry shook his head in laughing exasperation. "I don't even think Fred and George managed as many as this when they were here. They'd be proud."

Silence suddenly fell across the class like dusk closing in on a winter's day, as Dumbledore drifted into view. The pure white of his flowing hair and beard glinted in the sunlight that danced through the arched windows of that landing, dark purple robes fluttering in his wake. His face relaxed into a genial smile as he twinkled at the class, regarding them through his half-moon spectacles.

"Good afternoon," he said, looking along the row of Gryffindor seventh years, who instinctively tugged robes straight and stopped slouching against the wall under his penetrating gaze. "We have quite a lesson in store. Come in, come in." A flick of his wand and the oak door creaked open revealing a darkened interior to his classroom. With some hesitation the class trooped in, eyes slowly adjusting to the gloom after the bright sunlight of the corridor beyond.

"Wonder what this is for," Ron muttered, bending to pick up the stool he had just sent crashing to the ground. "Well, at least he can't expect us to do any writing in this sort of light, and that can only be a good thing."

"Ron!" Hermione exclaimed, appearing to sound frustrated with his lack of enthusiasm, yet through the darkness, Harry could just make out her reaching for Ron's hand, and a swift exchange of grins. He averted his gaze. There was little enough privacy at Hogwarts, something he knew all too well, and he certainly wasn't going to begrudge his two best friends a snatched moment of intimacy.

"Now then, Defence Against the Dark Arts has always been taught as simply that at Hogwarts," Dumbledore began, looking from face to face in turn. "Yet now we find ourselves in a situation where that is no longer enough. You are becoming adult wizards in a world where defence is inadequate, and you will need to battle with the Dark Arts in order to survive. You all know what it is like, either to experience personal loss, or to encounter the brutality of what those involved in the Dark Arts can do." His eyes rested briefly on Harry and there was a slight inclination of his head. "What I intend to teach you this year, as my time is brief, is how to fight against the Dark Arts; to show you how it may be possible to encounter them and live."

There was an awed silence across the classroom, a hush that was rarely heard in other lessons, total attention given to the wizard before them who spoke with such authority. Even Lavender had given up fiddling with her eagle feather quill, and it lay inert in her hands.

"These lessons will not be easy," Dumbledore continued, his eyes constantly roaming their frightened faces. "And at times may even involve an element of pain, perhaps more. However, you need to know how to face what is out there, and the best way of doing that is by experience. We shall begin with something you are all familiar with: Dementors."

A murmur rippled across the classroom, and faded almost instantly to nothing. Surely Dumbledore wouldn't bring a real Dementor to class for them to practise on?

"Can anyone tell me a spell that can be used on a Dementor?"

As ever, Hermione's hand shot in the air, narrowly missing Harry's glasses in her eagerness. Dumbledore smiled.

"Miss Granger," he said, gesturing for her to speak.

"The Patronus," she said. "It forms a barrier to protect you from the Dementors and drives them back so they can't drive you to despair, or perform the Dementors' kiss. Each Patronus is unique to the wizard that conjures it." Dumbledore nodded gravely, and his eyes travelled one pace to her right.

"Mr Potter."

Harry sat bolt upright and looked uneasily at the Headmaster.

"Yes?" he answered uncertainly, sincerely wishing he were elsewhere. The last thing he felt like doing was reliving the deaths of his parents, especially given his fears of history repeating itself with Ginny and their child.

"Perhaps you would care to demonstrate the Patronus for the rest of the class? Not on a real Dementor, of course, but rather an image of one, a mere fragment of the reality."

Harry nodded slowly, not really seeing how he could refuse, and got to his feet, moving towards the front of the classroom with a heavy heart. Dumbledore waved his wand, and with an expression of ferocious concentration, muttered an incantation beneath his breath. In the dimness of the light a darkly cloaked figure appeared, hazy, yet frighteningly real as it drew in a ghastly rattling breath, reducing the temperature of the room dramatically as it glided towards him. The voices of his deepest fears were there, although fainter than usual; his mother's final screams, unexpectedly blurring into those of Ginny when she had been hit by the Avada Kedavara only a year before. He couldn't listen to the memories; he knew that. He clutched his wand tightly, fixing his mind on the happiest thing he could find. Ginny. She loved him. She was to be his wife. To be with her always.

"Expecto Patronum."

The silvery mist shot out of his wand, forming instantly into the shape of the stag, which bent his noble head and charged the Dementor down, the illusion evaporating into thin air, and the stag returning obediently to Harry once more, acknowledging him with a bow of its great antlers, before it too disappeared.

Harry suddenly became aware of the rest of the class holding their breath with fear. A long drawn out gasp of relief came in unison as he looked up at Dumbledore.

"Very good," Dumbledore commented, smiling gently at him. "How did that compare with the real thing?"

"It was close," Harry admitted, before heading back to his seat. "Not as powerful, but apart from that it was just the same."

One by one, the class were called to attempt the spell, with varying degrees of success. Most managed a faint wisp of silvery smoke out of their wands after a few attempts, earning praise from their Headmaster, yet the real surprise came when Ron was faced with the challenge. A disconcerted look crossed his features as the Dementor glided menacingly in his direction, and Harry noticed him back up a little before standing his ground, and casting the spell with real determination. The silvery smoke that emanated from his wand took shape, heading purposefully towards the Dementor. Harry squinted for a second before he realised what it was, and glanced across at Hermione who was glued to the scene, her hand covering her mouth. The ghostly knight on horseback, reminded Harry instantly of the game they had played with Professor McGonagall's giant chess set, way back in their first year, and Ron's Patronus was certainly enough to dispatch the illusion with a brisk slice of it's sword. Applause broke out across the room, and Ron looked rather stunned with his achievement.

"Excellent," Dumbledore said. "Very well done, indeed. It seems that this spell is a particular strength of your family. Your sister produced a rather beautiful unicorn this morning, you'll be delighted to hear."

Ron blushed furiously, then grinned, and resumed his seat to let Hermione try her luck.

"What do you reckon?" he muttered to Harry. "Hers will be a copy of  'Hogwarts: A History'?"

Harry bit back the laughter, and watched Hermione carefully. She stumbled backwards, her face contorted with fear as the Dementor approached, soundlessly mouthing the words,

"Expecto Patronum. Expecto Patronum. Expec…" Her panic was clearly building. Ron leapt to his feet, looking anxiously at Dumbledore, who twitched his wand slightly, making the spectre draw in the trademark rattling breath of doom. Hermione screamed.

"Finite Incantem."  The figure vanished immediately at Dumbledore's command, and the darkness which had engulfed the room all lesson, steadily began to disperse, allowing daylight in. Hermione stood rooted to the spot, trembling from head to foot, shaking her head in desperation. Dumbledore spoke quietly to her, before turning to the rest of the class.

"Are you OK?" Harry heard Ron ask her, as the rest of the Gryffindors were packing their things away and leaving, having been dismissed with chocolate at the end of the lesson. Hermione shook her head, and buried her face in Ron's shoulder, shuddering with silent sobs. He hugged her tightly, and looked quizzically over at Harry, both of them completely bewildered about what had happened to her.

"It's a really difficult spell to do, Hermione," Harry said quietly. "The only reason I can do it is because of all of those lessons Lupin gave me back in the third year. And look on the bright side, at least you don't pass out every time you see a Dementor the way I used to."

"It was probably a complete fluke that I managed it," Ron added, taking his cue from Harry, and rubbing his hand across her back reassuringly. "You'll get the hang of it fast enough; you always do."

"It's not that," Hermione raised her tear stained face to look at them. She heaved a shaky sigh. "You know what I heard when I saw that Dementor?" Harry felt a chill run through him. He shivered suddenly.

"It wasn't… Not…not last March?" Harry's voice cracked. Hermione nodded, hot tears beginning to spill down her cheeks once more.

"It was awful, Harry," she choked, reaching for his hand and squeezing it. "It was like reliving the whole thing all over again. I could hear you yelling, and that awful chanting. I knew what they were going to do and I couldn't do anything to stop them. I thought… I thought you were dead and…"

"I'm sorry," Harry whispered, not knowing what else to say.

"It's hardly your fault," Hermione retorted forcefully, sounding suddenly a bit more like herself again. She gulped, and rummaged ineffectively through her robes for a handkerchief.

"Hermione," Harry said slowly, noticing that she still had a vice-like grip on his fingers. "You know what I heard this time?"

"Your mum before she died?" she guessed, her voice sounding rather wobbly. "You've said that was what you heard before."

"I did hear her," Harry admitted, and took a breath to steady himself. "But that wasn't all. I heard Ginny this time."

"Ginny?" Ron interrupted suddenly, looking rather pale. "What was she doing?"

"Screaming when Voldemort tried to kill her," Harry said, forcing back his emotions with some effort. The Dementor-like experience had made that hurt rather raw again. "Hermione, you've got to fight through that. There's nothing you can do to change past memories, but you can hang onto something really good. No matter how much they're trying to make me despair, I know Ginny loves me, and the thought of her strengthens my Patronus." He caught Ron's eye and felt himself flush, realising what he'd just admitted out loud.

"You know what I heard when Dumbledore set that Dementor illusion on me?" Ron said, looking thoughtfully at Harry, and running his hand nervously through his hair. "It took me back to the Hospital Wing, that night when we thought Ginny was dead. Brought all those feelings flooding back." He frowned suddenly, and glanced around the room, finding it deserted with the door closed. "Harry, it's just made me realise something," he added totally seriously. "It's made me see why you're going to marry her, and I've been a complete prat about it for the past few weeks." Harry opened his mouth to object, but Ron shook his head. "Shut up for once and listen," he insisted urgently. "I know anything could happen this year. You Know Who isn't going to let you get away with this if he finds out about it, so Harry, whatever I can do to stop him, and I mean anything, I'll do it."

Harry stared at him, not really knowing what to say. A great weight seemed to be lifted from his shoulders, as Ron's promise sunk in. Ron was with them on this now, not just as a disapproving bystander who supported them because he had to, but rather, by his own acknowledgment, because he wanted to fight this battle right along with them. Harry knew Ron well enough to understand that he would never make that sort of promise lightly, and 'anything' really did mean just that.

"Me too," Hermione whispered, squeezing his fingers one more time before finally letting Harry's hand fall. "Whatever it takes."

*****

Glancing up over a teetering pile of homework books later that evening, Harry saw the portrait hole swing open and a familiar figure clamber hastily through. He smiled across at Ginny, noticing the rest of the common room hastily gathering their belongings towards them. Of late, when Ginny had been around, quills had had a tendency to behave rather strangely after they had been left unattended for any length of time, turning people into a rainbow of colours when they picked them up, exploding, or occasionally taking flight and swooping around the circular room as if they were still attached to the birds they had originated from. Harry found the whole thing extremely entertaining, as did Fred and George if their enthusiastic letters to their little sister were anything to go by.

"How did it go?" Harry grinned, as Ginny flopped into a chair beside him.

"Flitwick gives the nicest ever detentions," she chuckled, rooting around in her bag for her homework. "I've spent the past two hours learning how to do Locating Charms, and finding stuff around the place for him. I even came across a hair slide I lost in there back in the first year."

"So it was a real punishment, then?" Harry teased her, feeling the familiar quivering sensation in his stomach as he watched her hair glow with a coppery sheen in the firelight. She giggled mischievously, and glanced back up at him, eyes sparkling.

"I'm just grateful Hagrid doesn't give detentions," she confessed, biting her lip. "I took the Dancing Dust down there with me this morning."

"And?" Harry suddenly had visions of Hagrid pirouetting across the lawns in a frilly pink tutu.

"Well, the Manticore was a bit surprised by it," she spluttered. "And having more legs than you do, his tap dancing routine was a little more complicated. A very impressive performance all the same."

"Ginny!" Harry burst out laughing. "You're going to get into real trouble if you keep this up for much longer."

"Speaking of trouble," she said, in a much lower voice as she leaned towards him. "You're going to kill me for this. You know I've got that detention with McGonagall on Friday?"

"For the Pyroclastic Parchment," Harry nodded. "Yes. What about it?"

"She stopped me on the way back up here tonight," Ginny whispered ruefully. "And she said I had to bring you to her office along with me. I think she wants to talk to us about… you know... things."

"Great," Harry said dismally. "So I'll just cancel Quidditch practise for a detention I haven't earned then, shall I?"

"Sorry," she looked troubled for a moment, and then her expression brightened up. She glanced around quickly, and seeing that no one was nearby, she wriggled closer to Harry and tickled his ear somewhat seductively with the warmth of her breath. "Anyway, it has the potential to be absolutely hilarious. Can you imagine if McGonagall tries to talk to us about sex?" Harry felt himself grinning widely at the concept of the rather formal Head of Gryffindor House tackling such a topic. "Potter. Miss Weasley," Ginny began, mimicking Professor McGonagall's clipped and disapproving accent to perfection. "What we must look at is the practical application of method."