A/N: In this fic, angels don't exist. They're human and always have been. I started writing this when I was watching an earlier season of Supernatural, so before I reached the Croatoan virus, the apocalypse, etc. I was thinking of a Walking Dead/Supernatural crossover, but it ended up being Supernatural + zombie apocalypse. Thanks for reading, and I hope you enjoy!
Sam and Dean stood side by side at the edge of a grave, watching the flames slowly burning. It was another job well done; with the remains gone, the vengeful spirit was finally at rest. Sam sighed and turned away, heading back to the Impala. Dean hurried after him.
"C'mon, Sammy, don't tell me you're having moral issues again."
Sam stopped as he was opening the car door. "Dean, you know how I feel about innocent people dying because of some –"
"Innocent? Sam, they killed people. For money. And you're saying they're innocent?"
"Dean, look, I –"
Dean held up a hand to stop him. "All right, you know what? I don't want to do this anymore."
"Do what?"
"I'm tired of us fighting, Sam. I miss the days where we hunted without having to choose who lives and who dies. We hunted things and we saved people, simple as that."
"Things are different now," Sam said in a quiet voice.
Dean exploded, his anger and stress uncoiling within him to become a turbulent storm of words. "Think I don't know that? My head isn't stuck in the clouds, Sam. I can see what's going on. These monsters are getting clever. They know our weak spots. But we have to face reality here. We can't save everyone. But that's not the same as saying we can't save anybody. We save who we can, and accept that. It's enough –"
Dean's phone rang, startling both of them. Dean fished around in his jacket pockets, searching for the device. He found it, then answered the call. "Hey, Bobby," he said.
Sam could barely make out what Bobby was saying, but now and then he heard a few clear words. Something about a virus? He watched Dean's face grow pale at Bobby's words.
"Yeah, we'll be there soon." He hung up and threw open the driver's door, getting in and starting the car. Sam slid into the passenger seat. The Impala shot forward with a lurch.
"What was that all about?" he asked.
Dean stared straight ahead, his mouth pressed into a thin line, his knuckles white as he gripped the steering wheel. He was nervous. "Nothing," he replied.
"Dean, stop trying to hide things from me. What did Bobby tell you?"
"You'll find out when we get there." He kept his eyes on the road, driving faster than the speed limit dictated. He didn't care.
The Impala rolled to a stop in front of Bobby's house. Sam and Dean got out and went inside. Bobby stood in the foyer, nervously shifting from one foot to the other. As soon as he saw the pair enter, he rushed towards them and hugged them tightly.
"It's good to see you again, boys," he said. Sam and Dean grunted uncertainly in response. Bobby let them go and held them each at arm's length, smiling and shaking his head. "My, you've both grown so much since the last time I saw you."
"Bobby, you all right?" Dean asked, eyeing him uncertainly.
"Me? Yeah, I'm fine. The world? Not so much."
"What do you mean?" asked Sam.
Bobby waved them over to his laptop. "Here, let me show you."
They gathered around the small screen, Bobby narrating as he showed them some pictures. "I've been hearing some rumors about a strange virus that's been going around. No one seems to have any cures for it, and the government's issued a warning saying that anyone who's got it should be killed."
"Killed?" Dean interrupted. "Why?"
Bobby glared at him. "I'm getting there." An image of red blood cells popped up. Black tendrils of what looked to be smoke surrounded a few of them. "See this?" Bobby pointed to the screen. "That's the virus. Doesn't have a name – not officially, anyway. It destroys the immune system, makes you cough up blood, that sort of thing. It's extremely contagious. Soon after being infected, the host is dead."
"Does this have some sort of connection to a spirit or a demon?" Sam asked.
"No," Bobby replied, looking at him strangely. "Not really."
"Not really? What do you mean, 'not really?'" Dean asked.
Bobby sighed. "It's a zombie thing."
"Zombies?!" Dean cried incredulously. "Zombies don't exist."
"They didn't exist," Bobby corrected. "Not until now."
"Wait, so, what, the virus kills the host and then repairs the body? Gets the heart pumping again?" Sam asked.
Bobby nodded. "Basically, yeah. But you see, when the host was alive, they lost so much blood that when they're… reincarnated, they want it back."
"So they attack living human beings and suck their blood out." Dean said.
"Animals, too. Anything and everything that lives and bleeds." Bobby replied.
"So what are we going to do?" Sam asked.
Bobby looked at him, his expression grave. "We're going to stop it."