Author's Note: Hey guys! So I'm really excited to get this one-shot out. It doesn't really have any action in it; pretty much just some fluff with Barry, Kara and Team Flash, but I just loved the idea of writing a fic where Barry had to spill that he had been to another earth and met Supergirl, since he never actually mentioned it in the show. And this was the product of that. Hope you enjoy! Leave a review and let me know what you think! Also, PSA, I don't watch Supergirl. I saw like half of the first season, but that was it. So bare with me lol. Also, you may have noticed I decided not to list this as an actual crossover. I did that for two reasons: one, because like I said, I don't know much about Supergirl and this focuses a lot on the Flash characters/perception of the events. And two, I don't like the fact that crossovers only show up in a crossover section. This is mostly written for the Flash fandom, so I want it listed here. Anyways, this is getting to be way too long of a note, so enjoy!

It was a relatively quiet Saturday at STAR Labs. That was to say, metahuman wise. It seemed that the lab could never actually achieve any other meaning of quiet. Cisco had one of his treasured playlists blasting from the sound system as he tinkered with a new device he was working on, and it was currently playing the song 'Bullet Train.' It was a personal hobby of the engineer's to find any song that possibly touched upon speed, a way to both amuse himself and annoy the everloving shit out of Barry (though he totally knew that the speedster secretly loved it).

Said speedster was sitting in the Cortex with Caitlin and Iris, his voice raised higher than usual as he talked with both girls, an attempt at being heard clearly over the music. Joe and Wally were originally supposed to be there as well, just to hang out, but had backed out that morning once Wally had heard news of a race car event happening in Keystone City. The young man had practically begged Joe to go with him. Barry and Iris had been invited too, of course, but both had declined - it was rare that the father-son pair got any bonding alone together, and this was a great opportunity.

"I swear to God, if another meta makes me late for work, Singh is so going to fire my ass," Barry was saying. "Julian isn't helping matters. He literally tattles on me every single chance he gets."

Iris snickered. "I'm sure you can handle it, Barry," she replied. "Singh likes you."

"But he does not like my chronic lateness or when I disappear midday. And Julian hates it even more. God, he's impossible to get along with."

"You'll just somehow have to manage," Caitlin chimed in with an amused smile. "You're a superhero, Barry. You've dealt with worse people than Julian Albert."

Barry rolled his eyes. "Thanks for the support, guys. Really, I appreciate it," he said sarcastically, but he was smiling as well. It was a rare treat that they got a chance to sit around like this, uninterrupted and acting like - well, like real people. Like there wasn't a city full of metahumans and other threats to deal with on a nearly daily basis.

Barry turned his attention to Cisco, eyeing the engineer as he continued to work, his face screwed up in concentration. "Cisco, what on earth are you working on?" he asked, voicing what he was sure everyone was thinking.

"Hold up," Cisco replied, his eyebrows furrowed, his tongue sticking out of the corner of his mouth slightly as he finished screwing something in place. Then, "Eureka!"

He turned around proudly, holding up a palm-sized device that looked almost like a radio, a green light blinking lazily on one side.

"...and that is?" Caitlin prompted, raising an eyebrow.

Cisco put his free hand over his chest and did his best to look offended, though it was quite overdramatic.

"Simpletons!" he said loudly, teasing. The trio before him couldn't help but let loose a smile, knowing they were about to get an explanation. "It's a tracker, sort of. Like...like my metahuman app and the tracker on Barry's suit combined."

"For what purpose?" Iris interjected.

"I am getting there, young Padawan," Cisco chided, and Iris rolled her eyes at the Star Wars reference. "It's to let us know of any metahuman or suspicious activity in the vicinity of STAR Labs," he explained. "An extra security measure, if you will. It'll alert us if anything is headed our way. That way, we can be more prepar -"

He was cut off as the device in his hand suddenly began emitting a high-pitched beeping sound, the lazy green light suddenly turning yellow, then red, blinking rapidly.

"Uh, does that mean -?" Barry began, suddenly very alert and standing from his chair, along with Caitlin and Iris. Cisco's face had morphed into an expression of mild surprise and panic, looking around the room as if something would happen any second.

And something did.

Suddenly there was a shower of glass raining down on them as one of the skylights above broke, an object sailing through at a high clip of speed and landing on the floor in the middle of the four members of Team Flash. Barry was milliseconds away from speeding over to get his suit, to change into it, to do something once he realized that said object was actually a person, until something in his mind clicked. He was staring at a girl clad in a familiar red and blue outfit. He sucked in a breath, because that didn't make sense. It couldn't possibly be -

But then the girl looked up, and her eyes met his, and both faces showed surprise as they recognized each other.

"Barry?" her voice rang out, breaking the stunned silence.

"Kara?" he asked.

Because yes, that was definitely who it was. Kara Zor-El, or Kara Danvers, dressed in her superhero uniform and staring up at him from the pile of broken glass on the floor. Kara from another earth, who most definitely should not have been here; shouldn't have been able to be here.

But yet there she was.

Barry was suddenly aware of three pairs of shocked eyes watching him, the gazes of his friends locked on him as they realized that the strange girl who had literally fallen from the sky into the lab was someone that he knew. They clearly wanted an explanation - and he needed one too, though of a different kind.

Shaking off his shock, Barry stuck his hand out belatedly to help her up. Kara took it, standing and brushing some glass shards off of her cape, and then pulled him into a quick hug, which the speedster was quick to accept; it had been a while since they had seen each other, when Barry had unexpectedly found himself on her earth. They pulled away after a moment.

"Uhm, so - you, uh - how?" was all the speedster was able to get out at first.

Kara laughed at his stuttering, and then opened her mouth to presumably give some sort of answer, but Cisco's voice cut through the air first.

"Okay, hold up. What the hell is going on?" he asked, looking between Barry and Kara and back again, clearly trying to come up with an explanation of his own but coming up blank. By the looks on Iris and Caitlin's faces, they clearly wanted to know the same thing. Barry didn't blame them.

"Uh, did I ever mention I accidentally traveled to another earth and met an alien superhero?" he asked, vaguely gesturing to Kara, who awkwardly waved.

His friends looked at him in stunned silence, Cisco's mouth actually dropping; Barry rubbed at the back of his neck.

"No? My bad."

"Okay, wait, hang on." This was Caitlin, the first to bring herself to be able to speak. "When did you…?"

Barry sighed, running a hand over his face. "I'll explain everything," he promised. "But, uhm, first things first." He looked back to Kara, and made another gesture with his arms towards the alien girl. "That's Kara Danvers, aka Supergirl. She's a superhero in National City about two earths away. Aaaaand she's kind of an alien. Kara, these are my friends Cisco and Caitlin, and my girlfriend, Iris."

Kara gave another little wave, extremely conscious of the curious, shocked looks they were all giving her, as well as Barry.

"And second...not that I'm not happy to see you, but how did you get here?"

Kara laughed once again. "It's kind of a long story."

"Huh. An alien who can open breaches," Barry was saying, eyebrows quirked up in surprise as Kara finished speaking. The five of them were all still gathered in the Cortex, sitting close together in multiple chairs they had dragged in to accommodate everyone.

"Oh hell no," Cisco interjected. "It's bad enough that there are existing aliens I didn't know about. But now you're saying there's one that has my power? Rude."

The engineer's eyes were glued to Kara as he spoke, still clearly quite fascinated with the fact that there was a real life alien girl sitting right in front of him, and one that Barry was friend with to top it off. Kara beamed at his exclamation.

"You can open breaches?" she asked. "That's great! That'll make it a heck of a lot easier to get home."

Cisco looked quite proud of himself, preening slightly, causing Barry, Iris and Caitlin to snort in amusement. Though they couldn't really blame him; Cisco had always been a huge sci-fi nerd. Getting validation from a pretty alien was like a dream come true for him.

"Okay, well, now that that's sorted out…" Caitlin looked towards Barry expectantly. "I believe you owe us a story." Iris and Cisco turned to look at Barry as well as the speedster gave Kara a smile.

"Yeah, man, explain why the hell we were never informed you met a hot alien superhero," Cisco demanded; Kara flushed slightly at being called 'hot,' and smiled back encouragingly at Barry.

"Okay, in my defense, it happened in the middle of when we were dealing with everything with Zoom," he said. "I didn't feel like it was the most opportune time to bring it up."

Iris's eyebrows furrowed. "You were able to travel to another earth when all of that was going on?" she asked. "We were all together, like, all the time. When was this?"

"Remember the day I was testing the tachyon device?" he asked. "Well, I kinda sorta ran so fast that I opened up a wormhole and ran through it."

"Wait, wait, wait," Cisco started, remembering the day it had happened. "So you mean to tell me that when you asked how long you'd been gone -"

"It was because I'd gone to Kara's earth," Barry finished his sentence with a nod. "I was there for a whole day, but when I got back here...virtually no time had passed. It was like I wasn't even gone."

"So time can work differently between earths?" Caitlin asked, more of a rhetorical question, looking intrigued. Barry shrugged.

"Yeah, I guess so."

Iris looked over to Kara with interest. "So does that mean when you leave here, it will be like no time passed on your earth? Or will it be more time?"

Kara shot a questioning look at Barry, but he looked just as perplexed at the question. It was her turn to shrug. "I have no idea," she admitted. "This is the first time I've been on another earth."

Iris looked back to Barry. "If you were on this other earth for a whole day, what did you do the whole time?" she asked. Barry and Kara shared a look at this question and smiled knowingly.

"Well, first I saved her from falling to her death off of a building," the speedster replied, motioning to Kara. "Or, at least I thought I did. Turns out she didn't need the rescuing, since she can fly."

"Guilty," Kara replied with a grin, remembering the look on Barry's face when it had happened.

"And we talked for a while, and I met some of her friends, and her boss, who insisted on calling me the Blur," he continued, making a face, which caused Kara to giggle.

"Wait, she knew you were the Flash?" Caitlin interjected, eyebrows shooting up.

Barry shook his head. "No. Well - yes. Uh, not at that point, I don't think, but she -"

Kara grinned. "Ms. Grant is smart," she said. "She knew it was weird that Barry showed up at the same time as a new superhero did. She said she would know when there was someone extraordinary pretending to be a nobody in her midst just like that," she added, snapping her fingers as Cat had done.

"You never told me that," Barry said with an amused look.

"Do her friends know about you too?" Iris asked; Barry nodded sheepishly.

"Waita go on the whole secret identity thing, man. Really," Cisco said.

"They're on an entirely different earth!" Barry protested.

"And Winn and James are trustworthy, I promise!" Kara said with a smile, coming to Barry's rescue.

"Well, what else happened?" Caitlin asked. "That wouldn't take an entire day."

"Let's see...went to a secret base where they deal with monitoring extraterrestrial activity, saw her spaceship, and fought some villains," Barry said nonchalantly, but gave Kara another grin. "Live Wire and Silver Banshee. One could control electricity and the other - well, she could scream like a banshee."

"You saw a real life spaceship!?" Cisco exclaimed, totally ignoring the villains part of what Barry had just said. "Dude, did you at least get a picture of it?"

"Tried - didn't go so well."

"Sounds exciting," Iris said with a laugh. "So how'd you get back?"

"Using my super speed, combined with the tachyon device and Kara's super speed, we were able to create a second wormhole back here."

"She has super speed too?" Cisco asked, looking awed. Barry nodded once again, shooting Kara a look, another grin forming on his face. Seeming to get what he was communicating, Kara grinned back, and suddenly they were both gone in a burst of golden lightning and a whoosh of air that sent papers flying everywhere, causing Cisco to curse. The pair of heroes returned mere seconds later, both with an ice cream cone in hand and an amused look on their face.

"Yeah, alright, memo received," the engineer said, starting to pick up some of the designs for his inventions as Kara and Barry laughed, licking their frozen treats. After a moment, Kara looked around at her three new acquaintances from Team Flash and smiled at them.

"Well, it was nice to meet you all," she said, and then looked back to Barry. "And it was great to see you again. But I really should be getting back. I don't want anyone to worry about me."

Barry looked slightly disappointed, but nodded in understanding. "Of course," he said. "Cisco can open up a breach for you," he added with a smile. "It was great to see you again too. Maybe we can meet up again soon, since we actually have a reliable way of getting back and forth between earths now," he suggested hopefully. Kara nodded excitedly.

"That'd be great!" she said, beaming. "I'd love for all of you to get to meet my friends," she said, looking to Caitlin, Cisco, and Iris.

"We'd love that too," Iris replied, smiling back at the alien girl.

"Yeah, you have to come back. I want to hear more about all this alien stuff," Cisco chipped in, and Caitlin laughed.

"That would be your top priority."

Cisco rolled his eyes, and made his way over to a spare table, where his Vibe glasses sat. He put them on his head and held his arm out, and in seconds there was a swirling blue portal in the center of the room.

"See you soon, then?" Barry asked as Kara stood, standing as well to walk her over to the glowing blue mass.

"See you soon," she agreed with a smile, wrapping her arms around him in a hug. She waved goodbye to the others, and then she stepped into the breach, disappearing in seconds. Cisco took his glasses off and stopped concentrating his energy, the breach collapsing in on itself to close as Wally and Joe materialized through the door of the Cortex, catching the tail end of the spectacle as it closed. Both men raised an eyebrow, looking between the four other adults in the room with a surprised expression.

"Okay, what'd we miss?" Joe asked.

Cisco snorted, placing his glasses back on the table.

"Too much."

Author's Note: Well, that's it! However, I am definitely thinking about a sequel in the future with another visit from Kara, where Joe and Wally get to meet her. I'll see what the response with this one is first! So like I said, review and let me know what you think!