So I was messaging with locitarose on Tumblr, and we started talking about the Flash and I made this joke about Flashes on other Earths. That convo ended up creating so many great ideas, and I couldn't help but have the desire to write a fic for it. So here it is. Set in the future after Leonard is rescued. References Tales of the Crook and the Assassin that's posted on AO3.

Earth-4. That's what Barry was calling it, despite the fact that as Earths went, Sara, Leonard, and Ray had only ever visited Earth-2 before a few brief times. Barry had gone to Earth-3 twice before, so he knew what that Earth looked like.

Ray (who had been mostly responsible for getting them into the mess in the first place) had decided to take it upon himself to repair the jumpship they had been in, which had suffered some significant damage. He promised that it would be fixed in no time and they'd all be home soon. Sara proposed to Leonard that they go and explore Earth-4′s Central City after two hours went by and Ray was nowhere close to getting done. Barry offered to stay and help out Ray while Leonard and Sara headed into the city. It was remarkably similar to the Central City they knew of their Earth in, well, everything.

"It's not a bad place," Sara admitted to him when they exited Earth-4′s Jitters with coffee. "I mean, there's no place like home, but this isn't as weird as Earth-2."

Not ten minutes later, they found themselves jumping into action to hold off a metahuman, because of course this Earth had them too. He had come out of the shadows (literally rising out of them) and now seemed to be controlling them to create shadow beasts to cause mayhem. Sara sprang into action immediately. Leonard followed, despite being unarmed (of course this was the ONE time he had left his gun behind because he thought he wouldn't need it). But Sara had passed him a few of her knives, so he wasn't totally unarmed as they found the meta and his shadows.

"Barry!" he heard Sara shout in her comm unit. Ray had managed to get those working somehow on this Earth so that they could keep in touch during their exploration of the city. "We need back-"

She stopped suddenly as a blur of red and yellow shot past her, creating a gust of wind that made her hair fly up momentarily. The blur zoomed around all the shadow creatures that the meta had created. The lightning left in the streak's wake caused the shadows to break apart and dissipate. The man who had been controlling them gave a shout of anger as the blur stopped suddenly, standing in front of Leonard and Sara. It was a man dressed in a dark red suit very similar to Barry's, except the lining on the sides was white instead of yellow. This was definitely not Barry though, as the man was too tall. But they knew this was the Flash of this Earth.

"Flash," the meta hissed in a slow, dark voice. "I've been wondering how long it would take for you to show."

"Leave them alone," the Flash replied, his voice vibrating and echoing throughout the city block. "This fight is between you and me, Shade."

"Then so be-"

The meta, Shade, never got to finish what he had been about to say before the Flash zipped forward. He moved too fast for Sara and Leonard to see everything, but by the way Shade went flying and hit the ground, they could only determine that the Flash had punched him out. Or more appropriately, knocked him out, as he didn't get up. The Flash approached him, his fists clenched as he stood by Shade.

"That was for kidnapping her," he said, anger in his blurred voice.

With the battle over, citizens were beginning to come out of the stores and buildings they had taken refuge in. Leonard noticed all of them were starting to applaud and cheer for their hero, except for him and Sara. They stood side by side, studying this Earth's speedster as he turned to them. He seemed to be shaking his head at a high speed, so his features were indistinguishable. But he tilted his head at the two of them before picking up the meta and speeding off.

"And there's the Flash here too," Sara murmured, looking in the direction he'd gone. "Not Barry though."

"This one's taller," Leonard agreed, watching as police cars began to pull up on the scene and officers began to take statements from witnesses. "We might want to get out of here."

"Sounds like a plan."

The two turned to go and leave the scene. Just as Sara took a step forward, the streak of red reappeared and vanished with her. Leonard gave a shout as the Flash sped away with her. What the hell was the Flash's problem? Why did he take Sara? Was the Flash here actually evil? Oh, he'd have fun enlightening Barry with that one if it was the case.

Something grabbed him suddenly and Leonard's world became a blur. Before he could even fight back, he found himself in an alleyway. Sara was next to him, looking around wildly. The confusion on her face probably matched that of his own. In front of them was their kidnapper, the Flash, with his arms crossed over his chest. His face was still indistinguishable, so they couldn't know who exactly this was.

"Can we help you?" Leonard snapped. "Or is kidnapping people off the street your idea of unwinding after kicking meta-ass?"

A low, echoing chuckle came out of the mouth of the speedster. The Flash of Earth-4 reached his hands up to the mask that came over his head. Leonard watched closely as he began to pull it back. He was a bit wary as to why this man was revealing his identity to him and Sara. They'd only just crossed paths, and it seemed like a very poor move. The guy must have been very stupid.

Or at least that was what Leonard thought until he saw the man under the mask.

It was him. At least, it was his Earth-4 self. The Leonard Snart of this Earth was the Flash. On this Earth, this version of him was Central City's hero. The man was a perfect copy of him, and Leonard felt like he was looking into a mirror. A very disorienting, very strange mirror. Suddenly, Earth-2, where he was the Mayor of Central City and married to Sara Lance, didn't seem as strange as this anymore."

Sara was looking between the two of them, stunned. "Whoa..."

"In regards to that question about help," Earth-4 Leonard Snart smirked at Leonard and crossed his arms. "I was about to ask if you needed some of that yourself. Given that you seem to be on the wrong Earth and all."

"You've had experience with that before?" Leonard scowled, crossing his arms over his chest and accidentally mirroring his counterpart.

"Believe it or not, you're not the first people I've encountered from another Earth," the speedster replied. "You're not even the first versions of myself and Sara that I've encountered."

Sara perked up a little at that. "So you know me on this Earth? What am I here?"

Earth-4 Leonard smiled. "You're a scientist at STAR Labs. Along with a few friends, you've been helping me with being the Flash. If you're looking for a way to get back to your Earth, she'll be able to help you with that. My fiancée's brilliant enough to do anything. And she'd love to meet another one of her counterparts."

"Wait, I'm a scientist here?" Sara laughed. "No way!"

Leonard's counterpart nodded. "I take it you're something else on your Earth?"

"Former member of the League of Assassins," she replied, coolly, making Earth-4 Leonard's eyebrows shoot up while Leonard smothered a grin. "We're both kind of in the hero business now. And did you say my counterpart is engaged to you?"

"We have been for a few months," Earth-4 Leonard admitted. "Are you two?"

"Not quite there yet," Leonard said. "We only got together a few months ago."

"Ah," his counterpart nodded.

"So you're the Flash on this Earth?" Sara continued, shooting a mischievous smile at Leonard before looking back at his speedster counterpart. "That's a surprise."

"I take it he's not on yours?" Earth-4 Leonard jerked him thumb at Leonard.

"Standing right here," he grumbled. It was still hard to wrap his head around the fact that he was this Earth's Flash. "And definitely not. The Flash on our Earth is-"

"Snart! Sara!"

Earth-4 Leonard whirled around as Leonard looked up to the entry of the alleyway. Barry Allen was standing there, dressed in his civilian clothing in place of his own Flash costume. Leonard did not miss his counterpart's eyes narrowing before he zipped forward and brought Barry back, pinning him again the wall. Earth-1′s speedster was looking around in confusion that turned to surprise when he got a better look at what Leonard's counterpart was wearing.

"What the hell are you doing here?" Earth-4 Leonard snapped, not looking pleased at all.

Barry still seemed to be hung up on who the man glaring angrily at him was. "Wait, Snart's the Flash here?"

"Already been established," Sara told him. "Look, put him down. He crash-landed here with us. He's okay."

Earth-4 Leonard looked over at the two of them before turning back to Barry and reluctantly releasing him.

"So, Barry Allen, huh?" Leonard's counterpart turned to him. "How do you know Captain Cold?"

Sara's eyes grew wide. "What?"

"Excuse me?" Barry looked stunned. "I'm who now?"

"That is not his name here," Leonard grumbled, glaring at his counterpart. "It's taken. And the kid's the Flash on my Earth."

It was Earth-4 Leonard's turn to look shocked now.

I can't ever stop laughing at this idea. But with so many Earths in the Flashverse, who's to say this isn't possibly one of them?