Chapter Fifteen
**Barry Allen's POV - From Earth-1**
As tired as Barry was of this day, traveling between universes was fun.
At first.
Now, though? Now he was getting worried.
He'd already traveled to one universe with an alien Supergirl superhero—Earth-38, Kara Danvers—and with their team-up, they'd become friends. She'd helped him when she didn't have to. Been kind. Been genuine. They had worked well with each other.
And now it seemed another Kara was going to help him as well.
Because apparently the multiverse had a thing for Karas helping Barrys who got themselves lost.
But this time, the help also came with a guy named Tony Stark, whose tech was so advanced Barry's head was spinning just trying to understand the basics.
He'd been running around the workshop for twenty minutes, examining everything, and his brain still felt like it was buffering.
"This is incredible," Barry breathed, staring at a holographic interface that responded to hand gestures. "How does this even, is this stable? What's the processing power? Where's the physical hardware?"
"Everywhere and nowhere," Tony said, not looking up from whatever he was tinkering with. "Welcome to the future, kid. Try not to drool on anything expensive."
What really blew Barry away, though, was the AI.
"J.A.R.V.I.S.," Tony had introduced it casually. "Just A Rather Very Intelligent System. He runs the house, the workshop, the suits, my calendar, my love life—"
"I do not manage your love life, sir," the AI interrupted smoothly. "I merely send flowers after you inevitably forget."
Barry's jaw dropped. "Your AI has... sass?"
"I prefer to call it 'adaptive personality programming,'" JARVIS replied. "But yes, Mr. Allen. Sass is an acceptable term."
"That's amazing," Barry said, grinning.
"He's a treasure," Tony agreed. "I'd be dead seventeen times over without him."
"Eighteen, sir. You're forgetting the palladium incident."
"Right. Eighteen."
Kara giggled from where she was floating cross-legged in mid-air, examining some kind of gauntlet. She caught Barry staring and smiled.
"It's weird, right?" she said. "The floating? It just became a fun habit."
"No, no, it's cool!" Barry said quickly. "I mean, I vibrate through walls sometimes, so who am I to judge?"
Apparently, Barry wasn't the first person to be stranded in another universe. Tony and Kara had been working on this exact problem, universal travel, multiverse mechanics, all of it.
They'd come up with a really cool wrist device that turned into a full suit, shrank a person down, and guided them through something called the Quantum Realm.
"It's like... tunneling between realities and multiverses at the subatomic level," Tony explained, pulling up a holographic diagram. "You shrink down past Planck length, where normal physics stops applying, and you can essentially slip between the cracks in spacetime."
Barry's eyes widened. "That's... that's brilliant. And terrifying. Mostly brilliant."
"It's very safe," Kara added. "We tested it."
"You tested it?" Barry asked.
"Someone had to."
"And you volunteered?"
"I'm invulnerable," Kara said with a shrug. "If it went wrong, I'd just be really small and invulnerable instead of normal-sized and invulnerable."
Tony snorted. "As you see it didn't completely work at she is so (tony thought about calling her SMOL but then remembered what happened to Hulk and thought better of it) Bite size or Fun size depending on your perspective.
This Kara was just like the other one, nice, genuine, a little awkward. But Barry could tell she was lonely. Bored, maybe. Like she was still trying to figure out what to do with herself in this world.
"So," Barry said carefully, "what's it like being a superhero here?"
Kara blinked at him. "A... what?"
"Superhero. You know, fighting bad guys, saving people, the cape and symbol thing." He gestured to her suit.
She looked at him like he was speaking a completely foreign language.
Tony jumped in. "Okay, so here's the thing, Flash. Little Bit here just woke up from a fifty-year nap near the sun—"
"It wasn't a nap," Kara protested. "It was suspended animation in my super cool alien pod."
"Potato, po-ta-to. Point is, she wakes up, immediately gets dragged into an alien invasion in New York—"
"With the Avengers," Kara added.
"—survives that, then goes to Asgard, gets adopted by the royal family, becomes the newest Princess of Asgard, and is apparently in line for some kind of godhood that hasn't kicked in yet." Tony paused. "Did I miss anything?"
"One of my new brothers, Loki taught me how to prank people," Kara said brightly.
Barry just stared.
"First aliens," he finally managed. "Okay, fine. I'm technically on a different planet right now, so aliens make sense. But now alien *gods*?"
"Technically, they're not gods," Tony said. "They're just really powerful aliens that ancient humans mistook for gods."
"They have literal divine magic," Kara pointed out.
"Advanced technology indistinguishable from magic."
"No, actual magic. I've seen it. Mother Frigga does sorcery."
Tony waved a hand dismissively. "We're workshopping the terminology."
Barry laughed despite himself. "You two are amazing."
---
**Kara's POV**
Kara showed Barry around the workshop, letting him examine everything Tony had scattered across various workbenches.
Tony didn't seem to care one way or another. Barry was leaving soon anyway, back to his own Earth, his own life. No point in being stingy with knowledge that when it could be used to help those like Barry who help people and could use a new source of income.
That's when Barry saw the arc reactor.
His eyes went wide. His mouth actually fell open. And he started making this high-pitched noise of excitement that reminded Kara of the sounds dogs made when you showed them a new toy.
"Is that, is that what I think it is?" Barry breathed, practically vibrating in place. "A miniaturized fusion reactor?"
"Yep," Tony said, not looking up from his tablet.
"That's...you can't just...how is this possible?!"
"Genius, billionaire, playboy, philanthropist," Tony rattled off. "Pick one. They're all equally valid answers."
Barry looked like he might cry. "This could solve the energy crisis. This could change everything."
Tony finally looked up, one eyebrow raised. Then he walked over to a filing cabinet, pulled out a rolled-up set of blueprints, and tossed them at Barry.
Barry caught them on reflex, then stared at them like Tony had just handed him the Holy Grail.
"That's the schematic for my first few arc reactors," Tony said. "Old models. I've improved the design since then—the new ones are way more efficient—but those will work. They're yours."
Barry sputtered. "I..I can't...what do I even...I don't have anything to give you in return!"
Tony smiled. "Name a hospital after me once you get rich off those designs."
Barry blinked. "What?"
"A hospital. Or a research lab. Or a building. Whatever. Just make sure my name is on it." Tony's grin widened. "I want my name on a building on a planet I don't even live on. That's the ultimate flex."
Barry laughed, clutching the blueprints like they were made of gold. "Deal. Absolutely. I...thank you. Seriously, thank you."
"You're welcome, kid. Now let me tell you about the greatest inventor on this earth." Tony walked off arm slung over Barry's shoulder as Tony talked on and on.
The next hour was spent finalizing the quantum realm device, calibrating it to Barry's specific universal frequency, and making sure he could actually use it without accidentally ending up in, like, Earth-763 or something.
Finally, the moment came.
Time to say goodbye.
Kara handed Barry the device, a sleek wristband that looked almost like a watch, and a small stack of paper blueprints.
"If you ever need us," she said, "you can use the blueprints' vibrations frequency to come back. They're tuned to this universe's specific frequency. Just... you know. Just program the wrist devise to the saved number 2 spot, I took the liberty to put your home universe in the first slot, you can hold up to 5 slots so you will have to figure out how to make this yourself if you wanna go more places. Tony said it should work."
"It'll work," Tony confirmed. "And we might be able to visit you in a few weeks. Now that I have a sample of your DNA, I can fine-tune the dimensional coordinates."
Barry froze. "Wait. When did you take my DNA?"
Tony's expression was perfectly innocent. "What makes you think I took your DNA?"
"Because you just said you have it?"
"Oh. Right. JARVIS?"
The hologram sprang to life between them, a complete three-dimensional map of Barry's DNA structure, his cellular vibration patterns, his metabolic rate, his neural pathways. Everything.
"As you can see," JARVIS said pleasantly, "we have comprehensive data on your physiology, Mr. Allen."
Barry looked around wildly. "When?! I think I would have noticed you taking my DNA! I'm the fastest man alive, I would have seen you!"
Kara tried not to laugh. She really did.
But the mental image of Tony somehow sneaking a DNA sample from someone who could perceive things in attoseconds was too funny.
"Let's just say I'm very good at what I do," Tony said with a smirk.
What Kara didn't tell Barry, what she kept to herself, was that she'd been the one to suggest getting the DNA sample.
Not for dimensional travel.
Not for science.
But because she thought the sparkly lightning effect when Barry ran was *so cool*, and she wanted to see if it could be replicated. Maybe incorporated into her suit somehow. Or just studied because it was pretty.
She wasn't about to admit that out loud, though.
Barry shook his head, laughing despite himself. "You people are insane."
"Thank you," Tony and Kara said in unison.
Barry pulled them both into a hug—one arm around each of them.
"Thank you," he said again, quieter this time. "For everything. For being awesome."
"Anytime, it is what I do, not everyone can save the day and look good doing it. See ya around, Flash," Tony said, patting his back awkwardly. "Try not to break reality on your way home."
"Come back and visit sometime, and like Tony said we might visit soon," Kara added. "Thanks for giving me the universal coordinates for the other me I think it would be fun to hang out with myself." She gave one last hug and saying, "if you need anything at all, like ever let me know, ok?"
Barry pulled back, smiling. "I will. Promise."
He strapped on the wristband, activated the quantum suit, and took a deep breath.
"Here goes nothing," he said.
The suit enveloped him in red light. He shrank down, down, down, until he was smaller than a molecule, smaller than an atom, slipping between the spaces in reality itself.
And then he was gone.
The workshop fell silent.
Kara floated down to stand beside Tony, both of them staring at the empty space where Barry had been.
"That was fun," Kara said.
"Yep."
"Think he'll actually make it home okay?"
"Probably. Kid seems resourceful."
"Should we have mentioned that the quantum realm can cause temporal displacement if he's not careful?"
Tony paused. "...Nah. He'll figure it out."
"Tony!"
"What? "He's *fine*."
Kara sighed and floated back up toward the ceiling. "Sometimes I worry about your definition of 'fine.'"
"Says the girl who threw a god at another god like a football."
"That was different."
"How?"
"All of you boys were being dumb."
Tony snorted. "Fair."
They stood there for another moment, then Tony clapped his hands together.
"Alright. Back to work. Those arc reactor schematics aren't going to improve themselves. And I've got a date with Pepper in two hours that I absolutely cannot miss or she'll kill me."
"I thought you said you didn't have a love life."
"I said JARVIS doesn't manage it. Totally different."
Kara laughed and went back to examining the gauntlet she'd been studying earlier.
Somewhere, in another universe, Barry Allen was probably freaking out about quantum mechanics and dimensional travel and the fact that he'd just gotten free arc reactor technology from a genius billionaire.
But here, in this universe, life went on.
And Kara was learning that sometimes, life going on was pretty okay.
Even if it involved way more interdimensional visitors than she'd expected.