I don't
Challenge info:Birthday Exchange Gift fic for E Greyjoy using the prompts :Remus/Petunia, Zombie!AU and Genre:Horror
Apologies if there's slight fluff and hurt/comfort elements.
This was written in three hours so it's not edited much either.

There was always something about Remus that scared Petunia. He was nicer than her sister's boyfriend but there was something wrong about him. He seemed so withdrawn and scared of himself. Petunia found herself staring at him when Lily and James brought Sirius and Remus as their plus one. She was afraid that they would be like Sirius but was relieved when Remus turned up in nice normal clothing and wasn't like Sirius and James. They came wearing robes which Lily 'fixed' to tuxedo's.
She looked at Remus as he seemed to wander from group to group like a lost butterfly. She played the gracious host as she greeted her guest with her fiancee. Nervousness filled her as she stared at the altar that they were going to be married. She remembered the time that Lily came to visit when she was taking the invitation. She was with James and Remus and both Lily and Remus told her she deserved better. James viciously told her that she deserved the bore. He was smirking and hated her. She hated him for taking Lily away from her.
Finally the wedding was about to start. She looked at her bridesmaids as they encouraged her and affirmed she was doing the right thing. They were jealous she found such a stable man to care for her. She felt like he only saw her. Eventually Petunia walked down the isle. She felt all eyes on her and some wet eyes but her eyes were on the priest and Vernon. Standing in front of the priest, it was like a nightmare, as he droned on and on. Finally he asked her if she would take him to be his lawfully wedded wife. Turning to Vernon as the image handsome fit man became a fat walrus that glared at her as he held out her ring with a smile. She hesitated and after a long silence spoke, "I don't"
Those two words were as loud as a shout in the silence. All around them the whispering began and she looked out at the gathered crowd. Lily and Remus nodded to her encouraging her and James looked shock. Vernon was silent but was growing redder by the minute. His hands gripped hers in a vice grip. She yelled out in pain and Sirius had walked up at her cry before forcing the bigger man to let her go. The priest turned to her, asking if she meant those words, and avoiding his gaze before meeting Lily's and then Remus's she nodded. She gathered herself before turning to the murmuring crowd.
"I apologize for the inconvenience." Petunia began trying not to think about what she was going to do, "Please feel free to stay for the snacks and the the reception will start in an hour at the appointed place. Thank you all for coming."
She walked down the isle again, dropping the flowers at Vernons' feet, and giving back his ring. He was shaking and Sirius and Remus walked behind her as Lily and James walked in front of her as if protecting her. She could feel the guests' gazes and the whispers were deafening. She couldn't follow through with it. Her sister was right about him and she would make one of the biggest mistake of her life marrying Vernon.
Her facade lasted until she was out of view of the guests when she latched onto Lily. Her sister held her in her arms and whispered that everything was going to be okay. Petunia didn't even know how she found the courage to say no by the time she went to her apartment. She just looked in in his eyes and saw what he would become in time. He accepted intolerance as normal and as much as she agreed with him, she never felt as strongly about it, and she didn't want to pass that on if they had any children. He was a dominating presence and she was shivering. Remus looked at her in concern. They all agreed that she needed to be alone but if Vernon visited, that she needed protection, and Remus volunteered to watch over her.
The phone was ringing she wished it would stop as Remus offered to answer it for her. He was on the phone for hours, each call five or ten minutes, before hanging up before it rang again. It seemed like everyone knew about the wedding and how she left Vernon at the altar. Some seemed to be encouraging or asking why, but the majority was abusive, rude, or shouting at her as she embarrassed Vernon. She couldn't believe it herself. She had just killed any chance for a decent job and money for the next month's rent. Vernon was certain to have called his friends. The expected notice came, she was going to be paid for her work plus two weeks severance pay but then was going to be laid off after that time. Remus consoled her as she tried to put herself together.
The next two weeks Petunia and Remus got closer as he helped her move in with Lily and James. The couple welcomed her into their home but eventually James agreed to let Petunia stay at one of his properties. She took the floo to the house and Remus followed her. Together they put back her home together. They were both sweating when Remus made the first move. He crossed the distance between them and they shared a long, passionate, and sudden kiss. They only parted when Petunia needed her breath. He was about to apologize but was silenced as her lips found his before his hands held her steady as she felt herself go week.
They split apart looking wide eyed and were at different ends of the room instantly. The line was crossed and the two former strangers would need to define their relationship again. Both red in the face they awkwardly told each other goodbye as she went to make dinner. Remus owled her the next day and she sent a letter back. Finally after three weeks they met again for coffee. Petunia had found a job as a secretary at another company. Remus looked ill, but was trying to put her at ease. She let him and they had a wonderful time before she had to go off to work. The job was at a biomedical company that produced vaccines and viruses. She was paid double from what she got from her old job.
It was an obvious mistake when a few months in there was an alarm and a gas was leaked in the ventilator shaft. The angry white fog filled the building and spread. She coughed as it filled her lungs. She was checked out when the police came after being put into quarantine. The results was that she was okay but would have to stay a while to see if she was okay. The next two weeks passed with her co-workers in quarantine. They were checked every four hours and sometimes one of them was taken away. Eventually after quarantine and many blood tests, they were allowed to go home, with pay for the two weeks and a bonus the traumatizing event.
Remus had learned from Lily about the event. He was there waiting for her when she arrived home. Sharing a gentle kiss they went further than before before ending up in bed. He asked her if this was what she wanted but she pulled him down so he was on top of her as she whispered it was all she had been thinking of. He told her that he was a werewolf and that if they did it then she could get in trouble. She refused to allow him to back out and already getting turned on Remus gave in.
Petunia woke up as Remus was panicking. He was pushing her chest as if to start her heart but she was fine. Looking at her breathing with her eyes open Remus fainted. She poured cold water over him after she dressed. He stammered and stumbled over words in a unintelligible mess. She tried to talk him down but it seemed to make things worst. Finally he burst out the truth in a single breath.
"I was worried because your heart stopped and you stopped breathing! It hasn't been beating for hours!" Remus looked at her with wide eyes.
"But I'm fine- see. I'm breathing just fine- there's nothing wrong with me." Petunia tried to comfort Remus but he waved his wand towards him and cast a spell. The spell glowed orange and he told her that green was for human and black was for dead. Then he held out his hand and she held it.
He cast the spell and she glowed black and she watched the glow fade as he cast it again. The result was the same. The spell appeared to say that she was dead. She paled unable to understand it as she fell to her knees. Remus held her close unable to speak. Neither of them knew what to do but suddenly Petunia knew why. She remembered the looks of shock of the others who were sent home. She knew they weren't sent home because she saw their bodies piled up behind in the large rubbish bin. They were being transported somewhere. She was given a clean bill of health when she was sent home.
The dorms that held them in quarantine had been overflowing at the beginning. They had to use cots. Eventually they were split into camps with full beds. The last two weeks were trying because every day there was less and less people returning. Her camp had 250 people that when she left for her apartment was down to under one hundred. She was told that she would be given a check up in the morning that she went to work in the next two weeks. She had the feeling that no one would return from it. Suddenly she pushed Remus away from her.
"Don't come near me! You could have already gotten what I have! If you are infected then I'm to blame…" Petunia began to babble.
"Unless you made yourself a zombie then it's not your fault!" Remus shook her , "Considering the amount of people let go, it's probably already spread to London and we live in a large international hub, Petunia. From what I've read it's air borne and they let the dead bodies out in the air for a short time. There were too many bodies to keep in an air tight bag."
"What can we do, Remus?" Petunia's eyes watered as she collapsed into his arms as he held and rocked her.
"Live and hope after all this, that we make it through, in one piece and together." Remus told her as they heard a knock on the door and someone yelling if everything was okay after all the shouting the neighbour heard.
"We're okay. Sorry for all the noise!" Remus yelled.
The man grumbled before yelling for the two of them to be more considerate of their neighbours. Remus relaxed as he let out a sigh of relief. They were safe for now. He wondered if they would continue to be safe for much longer. If there were others that were supposedly immune to the virus that were carriers and also infected London- then the world didn't stand a chance against this super virus. Petunia was sobbing in his chest and he wondered if it was more merciful to kill her now rather then let this virus take her. He held her closer, breathing in her scent- it was cinnamon and apple- but it was already beginning to smell rotting. He closed his eyes and wondered if he could stand the smell and when it got to bad if he would have the courage to do what needed to be done.