Elements of Infinity

"What you're talking about is possible," Starswirl admitted, "but it would take a lot of magical power. Too much for any one pony to cast the spell on the book and then cast a spell enabling themselves to survive in the vacuum of space. Too much for even an alicorn. And it would be at least a day before they could do it a second time."

Twilight rubbed her muzzle with a hoof. "Okay, so maybe I go get Starlight, then you can send the two of us through the book, one of us can keep us alive even though we're in space and the other can bring us back when we're done. Yeah! That could work!"

Starswirl sighed. "Twilight... your friends are either alive or dead. You going out to them will not change which of those they are. And there are many things that could go wrong. There are many unknowns. You and Starlight could end up dead! Would that be better than not knowing?"

"I don't know. I can't stand sitting here, not knowing what's happening, for a minute longer! I want to do something, something more than just waiting for more information!"

"You could try going to Earth and from there to find your friend. They're in the same galaxy as each other, you said. If you were to take an ordinary mirror, and replicate your modifications to my own mirror, with one of your books to power the link, it should create a pathway to their world."

"I looked at the possibility ages ago," Twilight grumbled sullenly. "It'll only work with a similar mirror configuration on the other end. That'll take a lot of time to set up, and Earth isn't even that close to them. Galaxies are big, Starswirl, way bigger than anypony knew in your day. Have you been keeping up with the recent astronomy?"

"I tried to, but I think they must be wrong. Most planets rotate around suns, rather than vice versa? Preposterous. At that point I didn't even bother."

Twilight sighed. "We can debate heliocentric solar systems some other time. For now, all you have to know is that galaxies are huge. Now, the distance between galaxies is even huger, so it's not feasible for us to get over there from here, but getting there from Earth is a stretch too. Unless they somehow got access to the Bifrost recently."

"The what?"

"It's a-"

"TWILIGHT!" Rainbow Dash burst in through the door. "Oh, hey, Starswirl. Twilight! Tony is in space!"

"What?"

"In a spaceship," Rainbow hastened to add. "Banner found him and told him Thanos was coming so he hijacked a spaceship and--I'm not making much sense, am I?"

"Not so's you'd notice, no."

"Here, just read this." She thrust her journal in front of Twilight's face. "Pinkie said I should let you know."

Twilight scanned the lines in front of her, then took only a moment to process. "Okay. Change of plans. Rainbow, leave the book here. Go get your suit, and anypony you want to take with you. We're gonna get you onto that ship."

"I have to ask," Doctor Strange admitted. "What is with that book? I've never felt a magic signature like it."

Tony shrugged. "A magic purple unicorn from another planet gave it to me. It lets me communicate with a blue pegasus from the same planet who can fly faster than sound."

"Fine, don't tell me."

"It's true. Oh, and it can apparently work as a portal. Don't ask me how, I don't get half the magiscience nonsense they talk about." He flipped some pages casually. "Seriously, look at these equations and tell me they make sense to you."

Doctor Strange leaned over the book. "Perfect sense. But they forgot to reduce that fraction."

Tony squinted. "That's a fraction?"

Before Doctor Strange could explain further, the book began to glow a brilliant white. Tony dropped it on the floor, pages spread out. "Give it some space. I don't really know how this works."

There was a crackle and a whoosh, and a tiny orange pegasus shot straight up out of the book. She landed on it and looked around with wide eyes. "Woah! Is this Earth? I've always wanted to see Earth!"

"...this is space..." Tony said after an uncertain pause.

"That's even cooler! Where are we going? Is it like flying? Where's the window? I wanna see space!"

"Is she wearing my suit?" Peter asked.

"Kinda," Tony hedged.

"Are you Iron Man? Rainbow told me so much about you!"

"Yeah, about that. Kid, where is Rainbow? She was supposed to be coming."

"She'll be along in a bit. I was just-"

The book whooshed again and shot out another pegasus. "Scootaloo! You were supposed to wait for me!"

"Yeah, but I was so excited to see Earth!"

Face met hoof. "This isn't even Earth! We're in space!"

"I know! They told me. Isn't it cool?"

"Yes, and that's great and all. I can't blame you for being excited! But next time, do what I tell you. Okay, squirt?" She ruffled Scootaloo's hair.

Scootaloo sighed. "Okay..."

Doctor Strange spoke up for the first time. "I have several questions."

Tony shrugged. "Then let's do introductions." He pointed to each of them. "Rainbow Dash. Scootaloo. Peter. Doctor Strange."

Rainbow waved. "Nice to meet you!"

"How do you guys even know each other?" Doctor Strange protested.

"...things went down..." Rainbow said.

"Not helpful."

Tony took over. "We got switched into each others' bodies one time. It was a weird few days. Rainbow actually fought in the Battle of New York."

"She WHAT?"

"Like I said, weird few days. Then they came over again to help us out with Ultron. That was when we got the books."

"How did you reach each other before that?"

Tony shrugged. "We didn't really. The only way to get over there was Thor's Tesseract. Which turned out to be an Infinity Stone, and now Thanos has it, so that's kinda off the table. Good thing we have those books, which it turns out are portals to each other. I still don't get how that works, and it bugs me."

Rainbow rolled her eyes. "Why does it matter how it works? It works, and that's the important thing. Freaking egghead."

"Yeah, well this 'egghead' designed that suit you're wearing!"

"Hey, I didn't say you weren't a cool egghead. Still an egghead though."

"Kids these days," Tony grumbled.

"Hey! I bet I'm as old as you!"

"I bet you're not."

"Five bits?"

"You're on."

"What are bits?" Peter asked.

"Our currency," Rainbow explained.

"Made of solid gold," Tony added. "Worth way more in our economy than hers. Makes it high-stakes gambling for me, low-stakes for her. Suits both our preferences at once. It's a stroke of genius, if I do say so myself."

"Anyway, how old are you? I'm 27."

"48."

"You're WHAT?"

"What can I say? I aged gracefully."

"But you do all that running around! And superhero-ing! You're so... spry!"

"Very gracefully."

Rainbow grunted. "Fine. You'll have to come over to Equestria to pick up, though, because I didn't bring any."

"What about all our other bets?"

She shrugged. "Same thing. I had other things on my mind, like getting over here." She turned, flicking her tail irritably, then paused and looked back. "Oh, I almost forgot! I need to set some rules. Well, just one, really."

Doctor Strange raised his eyebrow. "And that would be?"

"Nobody is allowed to die."

There was a confused pause. "What?"

"You heard me. No dying. Not allowed."

"I don't think it works like-"

"It had better."

Peter sat down by Scootaloo. "Is she always like this?"

"Not very often, but when things get really serious? She always insists that nopony can die. She's kinda intense."

"Seems like it. She any good at fighting?"

"Yeah! She's the best!"

"The best? You sure?"

"She can take out an entire changeling battalion single-hooved! Well, in the suit, of course. And she wouldn't anymore, the changelings are allies now, but earlier? She totally could've!"

"What are changelings?"

Scootaloo sat up eagerly. "Oh, they're so cool!" She began enthusiastically explaining to Peter, who seemed very interested.

Meanwhile, Rainbow and Tony's conversation had moved on. "Did you try the new modification I sent you?" Tony asked. "It was the most efficient way to configure your arc reactor for a smaller size."

Rainbow nodded. "It was great! But Twilight wouldn't let me use nanobots."

"Why?"

"Well, we're still way behind you guys in technology. Nanobots would have to use magic. Which would mean they would work great inside of Equestria, but if I left, there might be problems."

"Why?" Tony asked again, realizing that he was starting to sound like a child.

"Magic resistance. It's--I'm not the best at explaining it, but it's just like resistance to electricity, only magic can flow through a lot more stuff than electricity can, air and stuff. Thing is, Equestria has super-low magic resistance. Almost nonexistent. So the magic that works there probably won't work in other places. We're not completely sure why, but our main hy- hypo-"

"Hypothesis," Tony filled in.

"Right, that. Our main hippopotamus is that it's the fault of a guy named Discord."

Doctor Strange looked up abruptly. "Did you say Discord?"

"You've heard of him?"

"Only in the most terrifying of myths, but yes. If he's on your world, I'm very sorry."

"Eh, he's not so bad. Anyway, Twilight says-"

"Who's Twilight?" Strange asked.

"She's the purple unicorn I mentioned earlier," Tony explained.

"You called her a unicorn?"

"I simplified, okay? Get back to explaining."

Rainbow rolled her eyes. "Fine. Twilight says she thinks Discord probably, a really long time ago, used so much chaos magic that something in the world, whatever it is that causes magic resistance, just sort of broke. That's just our hippopotamus, though."

"Hypothesis."

"That's what I said."

Tony sighed. "You know what? Whatever. How'd you get around that problem? You must have, because you still have the smaller reactor on your wrist."

She looked down. "Yeah, Twilight did end up figuring out a magic fix. Basically, if I tap the reactor, my whole suit shrinks down into a bracelet on my wrist. It does still take a lot of magic--more than moving nanobots around would--but once it's in one setting it's totally stable. No energy cost to keep the suit up. Overall, it drains the battery less than maintaining nanobots would. And I've been working on adapting the other parts where we used a quick magic fix to run off actual electricity again. After Ultron, I didn't want to take any chances."

"Ultron? But your suit worked fine then!"

"It barely worked at all! The beams from my hooves were nearly useless as basic thrusters, not to mention as weapons! I was stuck doing hand-to-hand on the ground in clunky armor. I mean, it was good armor, but it wasn't good at anything else! When Ultron almost killed Hawkeye, I had to dump all my battery into the thrusters to get him out of the way in time! Still beat the speedster kid, though," she added smugly.

"He's as old as you are, Rainbow..."

"He WHAT?"