5 Saitama and Nightwing

As he walked through the sliding automatic doors of the Gotham Health hospital, Saitama ignored the several bewildered stares that he received from the near-empty emergency room as he made his way towards reception.

"Um…may I help you?" the lady asked from the other side of the grungy, fingerprint-stained service window.

"Yeah, I need to see a doctor about something," the costumed hero replied as he scratched his bald head. "I think I might have been exposed to a gas or something that's starting to turn me evil."

The receptionist stared at him blankly, her eyes blinking slowly at the blatant, flat way that the caped man had explained his predicament.

"That's- that's fine, we can have someone do a quick check up on you," the lady said through a nervous smile. "I just need you to provide me some ID and any insurance information."

"ID? Insurance? Okay…I don't have either of those," Saitama replied sheepishly with a sigh. "That's okay, I won't trouble you."

"I mean, if it's an emergency, we can't deny you medical attention, it's just- oh! Wow, it's you!" the receptionist exclaimed as she looked behind the caped baldy as another figured walked into the hospital.

Turning around, Saitama watched as a black-haired man in skintight, black costume strode towards him. A blue v-shape stretched across his chest from shoulder to shoulder, and a bat-shaped mask obscured the man's eyes and nose.

"Excuse me there, sir, could I talk to you for a second?" the stranger asked as he put a hand on Saitama's shoulder. "No need to fear, I'm one of Gotham's several vigilantes. I go by Nightwing, and it's a pleasure to make your acquaintance."

"Ah, you're a hero then," the caped baldy replied with a smile. "You were the one who was following me earlier, but I could sense that you weren't a threat. I'm a hero too, but I just do it for fun."

"I figured you might be, I mean, who else would wear silly costumes like this?" Nightwing said through a light chuckle. "But anyway, do you mind if we take this outside? I can hook you up with some top notch medical care on the house, if that's what you need."

"Do you mean free? Sure, lead the way," Saitama answered with a grin, before turning to leave with the black-clad hero. "Thanks for your help anyway, miss."

The receptionist was too preoccupied trying to take a selfie with Nightwing in the background to answer, where the 2 heroes promptly exited the hospital.

"Now, I didn't want to cause a panic in there, but I have a few questions that I need to ask you," the black-haired man began as he and Saitama walked down the darkened street outside, his demeanor becoming serious. "I'm going to put it bluntly. Did you kill the Joker and the Riddler?"

"Oh, the clown and the riddle guy?" Saitama asked nervously as he scratched the back of his head. "Yeah... that was me, but I didn't mean to. I mean, the clown appeared in one of the cities close to where I live, and I thought he was a monster at first. But riddles, I don't know. I didn't mean to kill him or his henchmen, but I did."

"Look, I know those two were horrible criminals, but my associates and I live by a code. We don't kill, we allow the judicial system to do its work," Nightwing explained as he continued leading the pair down the road. "Now, I know for a fact that you're not from this universe. I found traces of extradimensional matter by the wrecked Jokermobile. What was the Joker doing in your reality?"

"Heh, I figured that this place must be a different world completely, I mean I've never heard of Gotham town," Saitama said through a light smile. "But all the clown was doing in F-City was just driving around like a maniac. Oh, when I realized that he was Human and tried to take him to the hospital, he sprayed me with this gross gas."

"Joker venom?" the dark-clad hero asked as he rubbed his chin. "No, you'd be dead by now, it must have been something else. Do you mind coming with me to see one of my associates? He's got a lot of state of the art technology that'll help us figure it out."

Saitama stopped in his tracks as a question began to nag at the back of his mind. He couldn't explain it, but he felt compelled to ask as soon as Nightwing had again mentioned his associates.

"Your friend…who is he?" the caped baldy asked casually as he resumed walking behind the other hero.

"Well, I guess I might as well tell you since it's no secret that I work alongside him," Nightwing began. "He goes by the name 'Batman', and he's pretty world renowned when it comes to superheroes here."

"B-Batman?" Saitama asked as his face immediately contorted into a strange smirk. "Hehehe I don't know why, but I really want to meet this guy!"

An unexplained giddiness began to well up inside the bald hero upon hearing the name "Batman", and his emotions began to spiral out of control as his sanity lapsed for a moment. Nightwing instantly took notice of his change in demeanor, and stopped in his tracks.

"On second thought, maybe I'll wait a little while before I take you to meet him," the dark-clad hero said sternly as he eyed the caped man up and down. "Are you okay?"

"Hehehehe…HAHAHAH…hey…if I kill you, will that make Batman come here?" Saitama asked as his voice began to contort while his face twisted into a full evil grin.

"W-what?" Nightwing stammered as he quickly armed himself with some explosive batarangs from his utility belt and readied to throw them. "That laugh, I know that laugh. Whatever you are, be warned. I will not-"

Nightwing didn't even have time to finish his sentence as Saitama was suddenly upon him, and in the fraction of a second, was punched by the yellow and white-dressed hero. The poor man didn't even have time to process his fate as Saitama's blow obliterated his torso and sent his shattered limbs flying in different directions, while his head careened into a brick wall like a kicked soccer ball.

"HAHAHAHAH…hehehehe…oh crap, oh crap! What did I just do?!" the one punch man screamed in anguish as he looked upon the gore before him while his sanity returned. "I-I just killed that man. He was a hero, he wasn't threatening me! What the hell…"

A bead of sweat trickling down his bald head, Saitama sniffled in frustration as some random civilians took notice of the grisly murder and began to scream, forcing him to flee as people called for help.

"There is something wrong with me, there is something seriously wrong with me," the hero muttered to himself as he sped through the dark alleys of Gotham, fighting the urge to smile as he left Nightwing's remnants behind.