A/N: I DO NOT OWN ANY OF LAST OF US OR YU GI OH 5DS! ALL RIGHTS GO TO THE CREATORS OF BOTH!

Chapter 1: Immune

Yusei's eyes slowly fluttered open. He cringed a bit at a low light being shone on him.

"Nice to see you awake," said a woman's voice. Yusei looked up to see a dark skinned woman with dark brown, nearly black, hair. He slowly sat up and looked at the woman unsure, but stayed silent. "Name's Marlene. Found you passed out in the abandoned railway. What's your name?"

"Yusei," he answered slowly.

"You don't seem from around here. Where you from?" Marlene asked.

"A city called New Domino," he answered.

"Never heard of that city," Marlene stated. "How did you get out into the railway?"

"I'm not really sure. The last thing I remember is looking out at my home city and then a light," Yusei explained.

"Hmph," Marlene responded.

"How long was I out?" he asked.

"After we found you? About two days," she answered. "Surprised you haven't turned yet."

"Turned?" Yusei repeated. "What do you mean?"

"Roll up your left sleeve, Yusei," Marlene ordered.

Yusei gave an uncertain look but rolled it up as instructed. He was shocked to see a bite mark with almost blister like scars rimming some of it. "What the…?"

"Have you ever been outside the Quarantine Zones?" Marlene asked.

"What are Quarantine Zones? What are they separating?" Yusei asked.

Marlene gave a shocked looked. "Yusei, what is your home like?" she asked.

"It's pretty peaceful. We have duel tournaments, kids go to schools, and everything is just normal," Yusei answered.

"Yusei… As strange as this'll sound, I don't even think you're from this planet," Marlene stated. Yusei went wide eyed. "About twenty years ago, a huge pandemic destroyed the world. It was a fungal virus called Cordyceps Brain Infection, or CBI for short. When you're infected, the fungus quickly takes control of your mind and body. It makes you aggressive and want to kill everything. It usually takes only a couple hours after getting bitten before you start to turn. But you, Yusei, you've been bitten for at least two days."

"How does it even spread?" he asked. "And why am I not affected?"

"It spreads by either inhaling spores or having an Infected's body fluids enter your bloodstream," Marlene explained. "The most common way for the spread is to get bitten. It's said about over sixty-percent of the world's population is Infected. And the only way you aren't affected is because you're immune."

"How am I immune, though? And so these Quarantine Zones are keeping the uninfected from getting Infected?" Yusei asked.

"Yes," Marlene answered. "Yusei, come with me."

"Where?" he asked.

"To get you battle ready," she answered.

Yusei stood up and followed the woman out of the room. As they walked, people in bulletproof vests and ragged clothes greeted Marlene with a "Ma'am". They each held a gun of some sort. They looked at Yusei curiously as they walked passed.

"What is this place exactly?" Yusei asked.

"This is one of the Fireflies Headquarters. I'm the leader of the Fireflies. The thing is, military is always hunting us, killing us off. They see us as terrorists, so they've been shrinking our numbers down. It won't be long until none of us remain," she explained. "We need strong men like you, Yusei. It should take you about five months to complete some training. After that, I need your help to come with me. I need to sneak into a Quarantine Zone and get some weapons and supplies."

"But where will you bring the stuff after that?" Yusei asked.

"There's another base where we're planning on moving to in Salt Lake City, Utah," Marlene explained. "Can you help us with this stuff?"

"I think," he answered.

"Good," she responded. "Now, let me show you around and get you ready for training."