Introduction

It was an arm. Unnaturally pale perhaps, and currently enclosed in a glass case with little lasers flickering over it in a scan, but it was still an arm.

For the hundredth time in his life, Superman found himself wondering if his best friend had finally gone crazy. Sure, he had been sane—perfectly correct, in fact—the other ninety-nine times, but… an arm?

"Bruce, explain to me again why this is so important." He said, without taking his eyes off the appendage.

A snort came from the dark-clad figure at the computer. "Because it came from another dimension, that's why."

"Oh?" Other dimensional-beings DID tend to be rather nasty. "So have you found out to communicate with it yet?"

An annoyed sigh at his shoulder made him start slightly. "It's not sentient, Clark." Batman moved forward and began tapping on the monitor next to the box.

"You're sure? Some of these dimensional things…"

"I'm sure. I had J'onn look it over. It's just an arm."

"It might simply be dead. Then it wouldn't respond to J'onn."

"I also sought out Zatanna and several mediums and had them check into it. Granted, it's not entirely certain that they'd be able to contact a dead being from another dimension, but I'm pretty sure it's just an arm. The anatomy corresponds pretty exactly to it… the bone and muscle are nearly exactly the same as a human appendage."

"So it's just an arm."

"Yes."

"So… explain to me why this is so important again."

Another sigh. "Because it came from another dimension."

"Bruce, it's still just an arm. And according to you, a pretty normal arm. Why are you stressing out about…" Superman stopped, thought a moment, and corrected himself. "Why do you want me to stress out about it?"

"Dimensional ruptures have a habit of being problematic," came the response. "Especially when they happen repeatedly."

Superman blinked. "What?"

"Remember that explosion we had in the Metro tower last week?"

"Yeah. Knocked out the main generator and nearly caused a meltdown. We were on high alert for several hours, expecting an attack or something."

"Exactly." Bruce turned from the computer and faced the Man of Steel. "You remember the investigation we did, that was NOT a normal explosion. Yet we experienced no supervillain activity. That means that either they did something we haven't found out about yet, or none of them were behind it."

Clark frowned. "Not likely."

"That's what I thought. But I've yet to find any unusual activity that occurred that day. And then Question came to me."

"Q?" Clark's nose wrinkled in distaste. "And you listened to him?"

A snort as Batman turned back to the case. "I listened. I didn't believe him, but I told him to pursue his investigation, figuring it couldn't do any harm. Every so often his theories turn something up."

"What was this particular theory?"

Batman's face gave the slightest twitch. "Some kind of Mayan underground in the 'Soirree' hair salon chain, who were trying to bring about the end of the world through transportational magic."

Clark rubbed his face. "Remind me why he's in the league again?"

"Because every so often, his theories turn something up." Bruce gestured. "Like this. He checked up on other 'mystic disturbances' in the area, and found an unusual police report. A severed arm, found on the top of a nearby office building."

"That's what this is?" Clark studied the arm in the case. "Bruce, I'm not seeing the connection."

"Exactly." Bruce nodded, sliding his hands into the gloves fitted to the side of the box. "No one would, except Q. It happened about four hours prior to our incident, in a completely separate part of town. Even if I was looking into it, I might just think it was a random murder-and-mutilation job. But Q picked up on it because it was very similar to our situation. No explanation for it's appearance, no follow up, no evidence. It quite simply appeared on top of that office building. There was even a witness."

"What makes you so sure it's not just some random person's arm that we overlooked?"

"I highly doubt it's just 'some random person's arm.'" Here Bruce's gloved hands reached for the arm and picked it up. The elbow sagged slightly and the wrist hung limply from the arm as he turned it over and laid it back on the glass bottom, palm facing upward.

Clark stared at it for a moment. "Why," he said carefully, "would someone have a mouth in their hand?"

"That," Bruce said, "I don't know."

A/N: This story is partly inspired by ErikArden's "Healing the Spirit" (Which is on hiatus), and partly inspired by Itallia's "Humane Studies" (which was left unfinished.) I didn't want to start posting it at first, in the fear that IT would remain unfinished, and I make it a point to finish everything I begin. But I started writing and... well, it was too cool not to post.

So. I've started. And I intend to finish. But if you don't want this story to end up like those other two awesome stories, you could send me a line and REVIEW it. That's always an incredible motivation.

This is a Naruto story that will cross over with the DCAU, meaning Justice League Unlimited and Teen Titans. I should warn you, there will be MASSIVE manga spoilers in the coming chapters, especially the next one. I basically assume everything up to 479 has happened. Justice League, however, I will try to keep in canon... the events are supposed to take place after "Destroyer"

Pairings will be NaruHina and BM/WW at least. Maybe more.