Not just a cheesy Halloween oneshot. This is a full-length story with a plot

Important: This is taking place between season 2 and season 3. It is AU in which Barry never ran back in time to save his mom, and Flashpoint never happened. It's been two months since his dad died and Zoom was defeated. Barry is still grieving, but he's slowly starting to move on and be himself again. Jesse and Wells are back on their own earth, Wally and Caitlin don't have powers, and Cisco isn't grieving his brother, who is still very much alive in this timeline. Also, Barry and Iris are not together. She's giving him space while he figures things out and grieves his dad.

Earth 12

He really wasn't up for this today. Really, he was kind of getting sick of it already this week, but today, especially, Barry really didn't want to do this. He didn't even want to be at STAR Labs right now.

As he was in the elevator on his way up to the cortex, Barry's phone started vibrating in his pocket. He pulled it out and checked the caller ID, groaning quietly as he looked at the screen. It was Iris—again. She and Joe had been trying to call him all day, and Barry had been intentionally not answering.

Barry hit ignore on the call and put his phone back in his pocket. He knew why they were calling.

It was March 18th, the anniversary of his mother's death. Barry had been trying hard not to think about it all day. This day was hard for him every year, and he usually did his best to ignore it, but it was hard to ignore, especially this year now that his dad was gone, too. He had tried to go to work this morning so he could keep his mind occupied, but he found that he was too distracted to focus on anything that he was working on, so he left around noon, taking a half-day.

Cisco and Caitlin had clearly forgotten. Or maybe they just didn't know. Previous years, Barry had just avoided them, telling them he was busy, and they hadn't questioned it. They probably didn't even know what day today was. He had tried telling them he was busy again, but Cisco insisted he come in so they could work on their latest project.

They were currently trying to map out the multiverse. They wanted to know what each earth held, and they especially wanted to know if there were more enemies like Zoom lurking on other earths, ones that could eventually become a threat to them in the future. Barry wasn't entirely enthusiastic about the project. Traveling to different earths was exhausting, and he was worried that doing it was going to cause more harm than good. People just weren't meant to simply jump back and forth between universes at will. They were separated for a reason, and Barry had a bad feeling about what they were doing.

He had already been to five different earths. Earth 2, they already knew about. Earth 38, Barry had been to a few months ago when he had met Kara. But he had also been to three others now.

"You ready to explore a whole new world today?" Cisco said excitedly when Barry walked into the cortex.

Barry sighed and plopped down into a chair behind the cortex desk.

"Do we have to do this today?" he asked wearily, "I don't think I really want to see the other earths anymore."

"Why not?" Cisco asked incredulously, "You have the opportunity to see entire other worlds! Why wouldn't you want to see them?!"

"Because they're awful, Cisco," Barry said seriously, "I don't want to see any more. That last one…"

"Okay," Cisco said understandingly, "So Earth 3 wasn't very friendly, but—"

"It was evil, Cisco," Barry said, cutting him off, "I was evil. Everybody was evil. It was awful."

"Yeah, but now we know to not ever go to Earth 3," Cisco reasoned, "This may not be fun for you, but it's good for us to know which earths are good and which ones…kinda suck. This is important."

"I know it's important," Barry said, rubbing his eyes tiredly, "I just—"

"And Earth 5 wasn't so bad," Cisco pointed out, "You said nobody had superpowers there. Everything was normal."

"Yeah, but Earth 5 Barry Allen was a drug dealer," Barry said flatly.

Cisco couldn't help but laugh.

"I'm sorry," he choked, "But I still find that kind of funny."

Barry didn't laugh. He just sighed and leaned back in his chair.

"And Earth 23 was just a wasteland," he sighed, "Everyone was dead."

"Yeah, that was a bummer," Cisco agreed, nodding seriously.

He pepped up quickly, though, and moved closer to Barry to sit on the desk next to him.

"But I've been doing some vibing," he said excitedly, "Earth 12 looks really nice, Barry. I don't think you'll have a bad time exploring that one. It looks kind of fun to me."

"What's so fun about it?" Barry asked skeptically.

Cisco chuckled.

"I didn't see much," he admitted, "But there are other superheroes there—that, I know—and they seem really friendly to me."

Barry sighed.

"Fine," he agreed, "I'll go to Earth 12 and scout it out, but that's it for this week. Then I'm taking a break from all of this."

Who knows? Maybe going to Earth 12 would help take his mind off things. At the very least, it would get him away from everything here. If he wanted to avoid Joe and Iris and their overbearing concern, what better way to do it than by going to a different universe?

"I'll get the treadmill ready," Cisco said excitedly.

They had figured everything out. Jumping to different universes was somewhat easy for Barry now. He could do it just as easily as he could run back in time. All he had to do was run on the treadmill using Wells' tachyon device while focusing on where he wanted to go. It was a lot like time travel really. He didn't even require Cisco's help with it anymore.

Cisco had even devised a way that they could stay in communication with Barry while he was in another dimension. He had applied special tech to Barry's coms and his suit so they could monitor his vitals and speak to him across different dimensions. The technology worked very similarly to how his vibing goggles worked.

Caitlin walked into the room as Barry got up on the treadmill.

"Now, Barry," she said sternly to him, "Make sure this time you take a breather once you've made it to Earth 12. Last time you didn't listen to me, and you nearly passed out. Jumping dimensions depletes all your blood sugar, so be sure to eat something this time once you get there."

Barry gave her a simple thumbs-up in response as he attached the tachyon device to his chest.

"Alright, ready, Barry?" Cisco asked excitedly.

"Ready," he said quietly and then started to run.

He picked up speed quickly—thanks to the tachyon device—and soon he was just a blur to Cisco and Caitlin. Barry soon found himself surrounded by light, by speed force energy. He tried not to look at the confusing images that flew past him as he ran, knowing it was better not to see them. He just thought of Earth 12 and focused on getting there.

Focusing hadn't exactly been his forte today, though. His mind had been preoccupied with other things all day, and Barry couldn't help but think about how the first time he had run like this, he had been going back to save his mother, only to be stopped by his future self. He never wanted to go back to that night again. If he could, he would go back to a different time to see his mother, even if it just meant seeing her for only a moment.

But he couldn't go back in time. Barry knew that. He knew he could change things drastically if he did, and the results could be devastating. He just wished there was a way he could see his parents again without time traveling. He had gotten to speak with his mother when he was in the speed force, but Barry was still unsure if it had really been his mother he was talking to, or just the speed force, or maybe a little of both.

He couldn't ever talk to her or his father the way he wanted to. He couldn't talk to the dead, and Barry just had to accept that. He would never truly see them again, at least not in this life, and that solid fact left an empty void in his heart every time he thought about it.

Barry was suddenly engulfed in a flash of light as he reached his destination, passing through the wormhole he had created. That light quickly vanished as soon as he reached the other side, though, and Barry quickly found himself surrounded by darkness.

A thick heavy darkness seemed to press in on him from all sides, the chill in the air feeling harsh in his lungs, as if the air itself was leeching the life right out of him. He couldn't see anything. It was all just a dark void. But Barry could feel. He could feel a heavy sense of dread and despair in the air surrounding him, and somehow he just knew.

This was not a place where good things happened. This was not a place where he was supposed to be.

Barry woke up to a steady beeping sound. He didn't even remember passing out. Had he forgotten to eat or something and passed out while running? He could remember running on the treadmill just before passing out. That must have been it. He just didn't eat enough.

But then Barry remembered. He hadn't just been running. He had been trying to jump earths. He had been trying to go to Earth 12, and he was probably there now.

Barry's eyes snapped open instantly at the thought. He looked around him, expecting to find himself in a whole new world. Instead, he was surprised by how familiar everything looked. It looked like he was in the med bay in STAR Labs, laying down in one of the medical beds there, hooked up to a heart monitor which was beeping steadily. And then Barry heard a familiar voice.

"Oh, my God!" Iris cried, rushing over to the bed as soon as she saw that his eyes were open, "You're awake! Barry, you scared us half to death!"

"What happened?" Barry asked immediately as she hugged him.

"God, you're still cold as ice!" Iris said as they broke apart.

Barry did feel cold. His entire body felt like it had been dipped in icy water, and he was shivering terribly despite all the blankets covering him.

"What happened?" he asked her again.

"We were hoping you could tell us that," Cisco said, entering the room with Caitlin and Joe, "We don't know what happened. You were gone for two days!"

Barry's eyes widened.

"T-two days?" he asked incredulously.

"Barry, where were you?" Caitlin asked seriously, "Cisco tried vibing you, but all he saw was…"

She looked over at Cisco, who spoke then.

"All I saw was endless, crushing darkness," he said quietly.

It started to come back to Barry then. The darkness. The despair and lingering sense of dread in the air. He didn't know why, but he was scared. Something there had really scared him. He just couldn't remember what that was.

"I don't remember much," Barry admitted, "But I know one thing: I'm never going to Earth 12 again."

The others all looked at each other and Cisco cleared his throat.

"Barry," he said, his voice hardly more than a whisper, "I don't know where you were…but it was definitely not Earth 12."