I don't own the HP universe, nor do I make any money of it. And my name isn't J.K. Rowling. Edited for spelling mistakes.
Consider this one shot as a test, experimenting with different characters than the magical trio, and testing out how to write an action scene.
Luna was having a splendid time. Bill and Fleur looked perfect together, the party was incredibly sweet, and she could wear her yellow dress. It was so rare for her to be able to wear her yellow dress these days. At school, grey uniforms were the dress code, and even if it wouldn't be, Hogwarts was hardly the place to wear yellow dresses. Her fellow students already harassed her enough as it was.
But here, amongst her friends, she could be herself. And even though that dress robes might have been more appropriate to the wedding, everyone accepted her as she was, and the yellow dress just fitted the occasion. Yellow was for Luna the colour of luck, and she hoped that it would bring luck to the newlyweds.
Then the wedding party was unceremoniously crashed by a shape made of light. It was Kingley's patronus, and the message it brought wasn't one of happiness. "We can all use some luck right now", Luna mesmerised when she heard that Death Eaters would be arriving soon. Only a few seconds later, there was no time anymore for further daydreaming. With the arrival of several black cloaked figures, hell broke loose.
They arrived in large numbers, and didn't take the time to introduce themselves. Soon the air was filled with terrified screams, and red and green flashes could be seen in and around the tent. The Death Eaters weren't hesitating one bit, immediately resorting to killing curses or other destructive curses.
A black shape solidified mere yards away from Luna. As Luna locked her eyes with the assassin standing closest to her, for the first time in years the dreaminess left her eyes, and she stared hard into the eyes of the Death Eater. For a moment, the guy stood still, perplexed at her defiant look. Had she recognised him? Oh, she knew who he was, even with the mask. Lucius Malfoy.
Another figure materialised out of black smoke next to Lucius. And contrary to him, the new arrival didn't take the trouble to conceal her face. Nor did she take the time to stare back. As Bellatrix launched an unforgivable curse towards Luna, the girl in the yellow dress felt herself being pushed out of the path of destruction. Falling back on the floor, another body tumbled over her. "Sorry Luna..." Neville whispered in her ear, before he turned and launched an Expelliarmus charm back at where the danger had come from. But Bellatrix wasn't there anymore, she was already launching another attack at Harry, Ron and Hermione.
To her relief, Luna saw her friends apparate away before the spells could do any harm. So now it was time for them to get equally out of here. But where was her father? Looking around, people were quickly vanishing to safer places, while others were being cornered by the cloaked figures. Soon they would be outnumbered, and still more Death Eaters were arriving. She noticed her father in a far away corner, hiding behind a table that was turned on its side, and firing spells towards the black figures. Only then did she notice that he was shouting something. Her name. She knew she had to get to him, right now. He wouldn't leave without her, and she wouldn't leave without him.
As she got up, she suddenly realised that Lucius was still there, watching her, and his wand slowly got up, aiming straight for her heart. She realised with a pang that she was an easy target, standing out with the yellow dress.
She brought up her wand, but she knew that she was going to be too late, unless... With her wand still pointing to the grass in front of her, she whispered "Reducto". The result was an explosion of grass and dirt, which was enough to confuse Lucius for a moment. It was all she needed to scurry of to the side, hiding behind a large sofa, where she found Neville again. "I thought you were done for, what took you so long!" was the only thing he could exclaim. Next thing they knew, the sofa was suddenly burning, flames licking at their hair. Malfoy had aimed an Incendio curse directly at it. They only had a few seconds to decide what their next action would be...
"Neville, on my mark, we need to run to our right, heading for the exit, ok?" At Neville's nod, she added "But first, I would like you to try and fire a spell at him from above the seat, through the flames. It doesn't matter which spell, just take one that you're sure you can manage!" Again Neville nodded, as unsure as ever, pointedly aware of his clumsiness. Luna pitied his self-doubt, and would have said something to comfort him, to help him build up his self-confidence. But now was hardly the moment, so she bit her lip and whispered in his ear. "You'll do fine, now, fire!"
To her surprise, Neville got a determined look on his face and shot of 2 spells in quick succession: a jelly-legs jinx, rapidly followed by an Expelliarmus charm. Lucius blocked the first one easily, but had a bit more difficulty avoiding being hit by the latter. Luna took the opportunity to perform a small bit of intricate magic her mother had taught her in her childhood. At the left side of the sofa, now a fiery mess of flames, she created a wind that shaped the dust from the ground and smoke from the fire into a screen that obscured the line of sight.
She saw Neville preparing to run towards the screen, but she whispered "The other side!" while pushing him roughly to the right side of the sofa. There was no time to waste now. Even before they had emerged from behind the sofa, she had cast a disillusionment charm on both of them. It wasn't much, but it was all they had. She fiercely hoped that Lucius' attention would be on the obvious distraction, not on the one that actually required some insight to notice.
It worked as a charm. Lucius was still thrown off balance enough from Neville's spells that he acted on the dusty screen as Snape on the opportunity to take away points from a Gryffindor student – nothing else mattered anymore. Determined not to let them get away, he fired curse after curse into the thick screen of fog. He never even thought of looking at the other side, where blurred shapes were hurriedly moving towards the exit.
The distraction seemed to be working, they were almost out of harms reach... until they made a hastily exit of the tent. Outside they almost bumped into another Death Eater – this one not masked, but not known to Luna & Neville – who was making his way in. The close encounter broke the disillusionment charm, and Luna's yellow robes made it quite painfully clear to everyone that they weren't part of the attackers.
As Luna threw herself to the right, and saw Neville doing the same to the left, a bright green flash passed through the space that they were occupying just a split second before. Avada Kedavra. That was the way of the Death Eaters, no questions asked, kill before you think.
Their attacker decided to keep his aim on the male of the couple that had unexpectedly emerged. After all, what would a girl be able to do? And with her yellow robes, she would make an easy target later on. Preparing himself for another killing curse, he took carefully aim at the boy, who had tripped and was sprawled helplessly on the ground.
Horrified, Luna saw what was happening, how the Death Eater kept his wand trailed at Neville instead of her. It was a mixture of immediate relief – she wasn't targeted – and dread for Neville. She had to do something, immediately. Aiming her wand at the Death Eater, she spoke the first curse that came to her mind.
"Reducto!"
The curse, fired from only a few feet away, had a devastating effect on the black robed villain. His body was flung away several yards, while some of his limbs stayed on the spot, unaffected by the curse. He didn't stand a chance, and was dead before he landed, his ribcage broken, lungs crushed and spine snapped.
Luna felt as in a daze. She stared at her hand, still holding her wand, pointing to where once her opponent was standing. When her gaze went down, she noticed that her yellow gown was stained with blood. His blood or her own, she didn't know. "Red doesn't fit my yellow dress" was the only thing she could think of. She had killed someone, for the very first time. Was she still any better than her opponents? They had killed, she had killed... How different was she now from a Death Eater?
Out of the corner of her eyes, she saw Neville getting up, rushing over towards her, and grabbing her shoulders. He was saying something, but she didn't hear him. Maybe he was asking if she was alright? She shrugged her shoulders. Then she noticed a familiar face appearing from inside the tent, Lucius Malfoy.
But Malfoy didn't have the time to act. Neville grabbed Luna tightly by the shoulders and apparated her away, as far away from this scene as he could. He knew it would take time to make her understand. Understand that what she did was good, that it had been necessary. That she had saved his life. He would be forever grateful to her for this. But that was not what she needed right now. She needed someone to support her, no matter what. And he was fully dedicated to this new purpose in his life. He would never let anything bad happen to her again. Never...
He couldn't have been more surprised by Luna's reaction when they appeared at the entrance of the Leaky Cauldron. He had expected her to be sad because of what happened, of what she had been forced to do in order to save him, and perhaps a bit relieved because they got out largely unharmed. But her reaction was quite different. Luna stared wildly around, recognising where she was, and then let out a loud wail. "No! I need to go back! My father, he was cornered... please, we can't lose more time!" And with a crack, she disappeared again.
Neville didn't think it over, he had sworn to himself just seconds ago to protect Luna. And that's what he was going to do, even if it meant going back into the thick of the fray. Because that's where she had gone, he was sure of it.
As he appeared back at the Burrow, he knew he had made a good decision to play it smart and apparate back just next to the garden shed, where he knew he would be out of sight. From what he could see, Luna hadn't done that. He could see her standing at the entrance of the tent, firing spell after spell inside, surprising the Death Eaters that were still cornering her father inside. She managed to stun 2 of them before they realised the new danger.
Xenophilius had been the only one still there, all the others had been either killed or had run off. Luna's father hadn't dared to apparate away, not knowing what had happened to his daughter. And he was fighting valiantly, holding off 5 Death Eaters on his own. But now Luna had quickly disabled two of them, and the tables were turning. Xenophilius recognised his daughter as the reason why only three villains were still standing, and was throwing his spells with renewed energy, severing the wand arm of a third opponent.
But Neville noticed from his hide-out what Luna hadn't seen, being utterly focussed on the battle surrounding her father. In the garden there were still some opponents. They had noticed the arrival of Luna and were preparing their attack, silently moving into position to be able to swiftly dispose of the girl in the yellow dress with red bloodstains... Neville couldn't watch this unfold any longer, so as he started running towards the tent, silently but fast, he grasped something in his pockets. When his hand came out, it was holding a tube of Bubotuber pus, freshly squeezed from his garden that same morning. It was a good thing he was forgetful, that's why he hadn't taken it out of his pockets before coming to the wedding.
Coming up behind the opponent closest to him, he cast a swift Silencio charm on his victim, and then threw the opened bottle at him. It wasn't a pretty sight, and must have hurt a lot. The Death Eater was incapacitated though, clutching his face as fiery red bumps started growing everywhere.
Meanwhile, inside in the tent, the battle only became more intense. Two against two, the remaining Death Eaters focussed their strengths on defending from the Lovegoods spells, assured that the noise would bring in other Death Eaters from in the garden. Luna, from the other side, started feeling the intensity of the battle, and everything was rushing through her head. The physical tiredness, the mental knowledge that she had killed a man and that she might have to do it again now if she wanted to save her father. But she wasn't sure she could bring up that strength again. She was not a killer, she didn't want to harm... But in this case, there was no choice. Her opponents wouldn't doubt, that much was obvious. And with every moment that passed, chances were increasing that their opponents would get backup.
Outside, Neville was on a roll. There were still eight Death Eaters inching closer to the tent, but they hadn't noticed him yet. As he inched closer to his next target, his hands were searching his pockets again for something useful to use in battle. It had to be something that would be quick and without noise, so he decided to forego his wand for now.
He had one other plant with him, a small stomp of a Snargaluff. When he had come to pick up Luna and her father for the wedding, he had been fascinated by the adult Snargaluffs in their garden. Xenophilius had been so kind to risk a few of his limbs to cut off a piece for Neville. He had stunned it, not to have any trouble during the wedding, and now his hand had found this seemingly dead piece of wood.
Crawling up till just behind his victim, Neville pointed his wand to the lump of wood, and whispered the Ennervate charm. "Huh?" what the only thing that the Death Eater could manage upon hearing the whispered spell behind his back. While he turned to see where the noise came from, a small Snargaluff was thrown in his face. It didn't hesitate, and wrapped its vines around the surprised guy's head. It was squeezing so hard, that blood was gushing from wounds all over the villain's face. Neville picked up the wand of his opponent, where he had lost it while struggling with the Snargaluff and dived in the bushes. It was just on time as several other Death Eaters turned to see what was making the noise behind them. Seeing their companion struggling with the stubborn small plant, some even laughed for a second, thinking he had set foot in one of the traps of the Weasley twins. After all, this was the house of the Weasley family, it was only to be expected that there would be some funny – albeit painful – traps there.
Out of the bushes, Neville took carefully aim with both wands, each wand tracing another opponent. When he was sure that he couldn't miss, he shouted at full voice. "Stupefy!" Inventiveness was over, it was time to plunge down into the action, head first, as a true Gryffindor. As the two targeted men fell backwards, the five other Death Eaters outside now knew his location, and a rapid succession of hexes and curses in his direction was their answer. It was all Neville could do avoiding the curses, and slipping in the occasional hex from himself.
One of the hexes by Neville actually flew over the heads of his opponents, into the tent and hit Luna's direct opponent directly into the head. As they guy fell down, and the mask flew off, they could see tentacles beginning to form in his face.
"Backup is close," Luna thought, "but are they friends or enemy?" She decided not to wait for it, and doubled her efforts together with her father to disable the last remaining Death Eater in the tent. Two against one, he was outmatched and soon found himself on the ground, bound with invisible ropes, the result of a successful full body-bind curse by Luna's father.
Luna ran the short distance to her father, and the moment she fell in his arms, the world started spinning and they arrived at her house, courtesy of her father's quick apparition skills.
Neville at the other hand was getting in a worse position. He still had 5 persons to deal with and the heat of the action prevented him to even think about apparating away. He would have been struck down before even being able to complete the apparition. And his opponents weren't using tickling spells...
His hopes completely disappeared when he heard the voice of Lucius Malfoy chanting an anti-apparition spell. "Now he can't leave, he's ours!" the voice of Lucius could be heard again wallowing in triumph. "No! He is mine!" a woman's voice came carrying over the noise of the spells.
"Bellatrix. So she hadn't left yet. This will get ugly..." His thoughts weren't exactly sheering him up at the prospect. Meanwhile his opponents were decreasing their crossfire, and were found engaging in a shouting match with Bellatrix. "He's as well ours as he is yours!" an unknown cloaked figure said. Bellatrix looked as she was going to crucio the guy just for daring to oppose her, but she settled on just one sentence. "Idiot, I will deal with you later."
Neville had taken the opportunity of the decreased fire at him, slowly backing down into the garden, where he hoped the anti-apparition ward wasn't strong enough. But he wanted to be far enough not to risk to splinch himself.
Entering the vegetable garden, he kept on backing up, all while sending as many as possible spells towards his opponents. But Lucius could be heard again muttering the anti-apparition charms. All hope was gone now, there was no way to leave, and he was still nicely outnumbered. To top things off, there wasn't much protection in the vegetable garden. After what seemed an century, but was in the reality not even two minutes of heavy spell fire, a Sectum Sempra curse passed in front of him, but still managed to slice a nice deep cut in his leg. "That's it, the end," he thought, "now way to defend myself against that many. And now I cannot even run away anymore."
As his legs gave way, his eyes closed from the impact on the ground. Opening them again, he was surprised to see a familiar thing. His head was lying next to a half grown Mandrake! He turned and saw Bellatrix approaching, savouring the moment, wand aimed at his heart. Lucius was only inches behind her.
"I am going to enjoy this!" was the last thing he heard from Bellatrix. The next word that could be heard was "Crucio!" Neville was in agony, in pain, in such a torment that he would have done anything to stop it. And then it stopped. Bellatrix was standing directly over him, eyes glinting with madness.
"Want some more? Yes, I think I want to see you suffer some more!"
There was no way out. So Neville did the only thing he could do, to save him from the torment. He grasped the Mandrake, and pulled. As it was yanked out of the ground, a loud, sharp wailing filled the air. Neville lay in the mud, blood coming from his nose and ears, while all around him, Death Eaters dropped to the ground.
"Heaven was soft and comfortable. Well, it had to be Heaven", he thought, "Hell could never be that comfortable." A touch... something touched him, his face. It was a gentle touch, as an angel would touch him. "Yes, he definitely was in heaven." A small smile formed on his lips, savouring the prospect. And then he heard the voice of an angel. "Dad, look! A smile! I think he's coming around!"
As Neville slowly opened his eyes, his smile grew bigger. It was hard not to smile if the first thing you saw when opening your eyes, were Luna's eyes, only inches away from yours.
"I'm not dead." It was more of a statement, than a question.
"You're not dead." It was a simple reply from Luna. And then she kissed him, full on the lips.
Neville recovered slowly but steadily, with the help from Luna. As he had been the closest to the mandrake, he had been the most affected. Luckily it had only been an adolescent one, not able to kill, but still able to perform serious injury.
Everybody present in the Weasley's garden had fallen prey to the Mandrake's voice. Luckily, its wailing had decreased after a while and when Luna came back with the recovery squad from the Order of the Phoenix, they could only hear it slightly. Still, two persons of their team had fainted trying to get closer. Luna, being the only one crazy enough to have ear warmers with her in the month of July, was able to get close enough to bury the mandrake in the ground again, and they had rushed in to help Neville and apprehend the Death Eaters lying around him.
They had wanted to take him to St Mungos, but Luna had been adamant that he would be transported to her house, insisting that she would take care of him. After all, he had taken care of her, he had shown that he cared. And she cared for him, very much even. That she had realised now. And that's why Neville woke up in heaven, while not being quite dead yet...
