She's fighting a supervillain - she hates that supervillain is even a category, but that's what she's doing - when the guy fires off some kind of portal gun, and then she's dealing with more than just the one guy.

She scans the sky for portals back. She takes in the fires, then the attack in general.

Her first impulse is to defend the city. This is a bad impulse to run off with without checking in on things - she doesn't know what the political or military situation is, and attackers aren't always the bad guys. If the Allies are trying to retake Paris, you...?

Well, you put out the fires, anyway. 

She puts her standard bubble-construct up for armor and flies up to the nearest skyscraper to check whether it in fact has anyone inside.

The top few floors collapse in flames as she moves in to check, but it seems like this one was empty. But a sniper in one of the other buildings has apparently decided her green glowing sphere is an acceptable target and she's fired upon. High-velocity kinetic rounds only, nothing exotic.

Well, naturally. This is what the bubble is for. The bullets bounce off, because she's practiced this, and she goes to check on the other buildings.

They're all mostly clear of living inhabitants.

There's a large cluster of people in the base of that one over there, however.

Strictly better than the alternatives, she supposes. She flies up to the highest inhabited level of the skyscraper and tones her bubble armor down to something still-protective-but-less-noticeable. 

"Hey! Anybody in need of specific assistance?"

There are a lot of armed and uniformed men and women inside! Many of them are now pointing said weapons at her. One in the back seems to be whispering a description of her into a communications device.

"Identity yourself," demands someone who may be an officer, judging from the insignia on the shoulder.

"Green Lantern 2814. Got shot through a portal just now and I'm very confused."

It's cool that her costume has a facemask, because she might just have to make herself scarce in a bit if this goes really really wrong.

"...says she's green lantern? No sir. She is green, sir. Glowing. Yes, sir."

"This is an active warzone. Who authorized your presence here?"

"Literally no one, I got shot through a portal about three minutes ago and this is where I got spit out? I did notice the warzone thing, I understand that this is a really bad time for you. If it would be better for me to leave then I can do that, you just looked like you might plausibly need some help on the not all dying front? I am a fan of people not dying."

The officer looks skeptical. "Corporal?" he calls over his shoulder.

"Inbound, sir. ETA-"

A streak of golden light interrupts the corporal's report and there is abruptly a girl in a sparkly dress standing between the soldiers and the Green Lantern.

"Hi everyone. What's going on?"

"I got shot through a portal!" she says, helpfully. "I'm wondering if there's anything I can do to help, but your people are understandably very concerned about the sudden unexplained interloper. That's about it on this end, I'm pretty lost. Sorry for diverting resources from the primary matter at hand, wasn't intentional."

"Yeah so when a strange magical girl shows up that's usually not a good thing. How about you and me hop a couple buildings over to talk so the sergeant can relax a bit."

"Sure thing," she says, and flies to one of the skyscrapers that she's pretty sure is abandoned.

Anneia follows, taking the distance in several great leaps, bouncing off the sides of buildings.

"So you said something about a portal? Where are you from?"

Hmmm. Assuming that supers are as thick on the ground here as they are at home, and assuming that they're as varied as they are at home, sometimes with access to honest-to-goodness magic, and carefully not making any assumptions about whether the person she's talking to is generally on the up and up, and knowing that a bunch of people are going to die if they somehow get to Earth and invade, even given the Justice League's obvious ability to oppose them -

Oa can handle itself, surely.

"The Green Lanterns are based on a planet called Oa. We're a peacekeeping force that spans the galaxy, so we get called in to deal with anyone similarly powerful who wants to make trouble. Unfortunately, the troublemaker of the day has a portal gun, and apparently he can send people pretty far away from where he is. I'm gonna try to get home after this, obviously, but I'm not in such a rush that I can't stop for anything." 

"Uh, yeah, so there's no planet called Oa or Green Lanterns in this galaxy."

"Officially pretty concerned about the strength of that portal gun, then."

"We don't have anything like that, either."

"Oh, the portal gun is new, that's no surprise. Green Lanterns are fairly structurally normal, though, I expect that wherever we are is far outside Oan territory."

"I mean, unless half the galaxy is 'far outside Oan territory' I think you might be from another dimension or something." Or just actually insane but that wouldn't be productive to say. And there's the weird mask and the weird costume and the weird green glow and all that together adds up to a whole lot of weird.

"That's possible. Might honestly have been easier than transporting me a couple galaxies over, though I've heard of both things happening. Ohh, I know," she says, and gives a mental command to her ring. "This is - yep, nope, comms are dead. Different dimension or profound interference it is."

"Okay, cool. So now that we've established you're not a whitesider here to break our trap before we can spring it, do you mind if we walk and talk? 'Cause the tanks'll be rolling in in about five minutes and I was supposed to snap their line about fifteen blocks north of here."

"Fine with me."

"Great." She hops down to the street and sets off at a quick run.

Karen flies, though she flies very close to the ground. Flying is easier.

"Isn't that a waste of power?"

"Fairly negligible. If I wanted to turn the tide of this battle by myself I would have to run some serious calculations, but I'm pretty sure that trying to win a war that you know literally nothing about is against one of the cardinal rules of diplomacy anyway."

It would be worth thinking about if she didn't have her backpack on her and her lantern in the pack, but luckily her past self has done her a solid here.

"Huh." Okay, yep, running on different rules. "Well, it's not like you could actually win the war from here. It's just one planet. And the Compact doesn't care much about it or the assault would have more magical support than that girl down south. Of course, the Domain doesn't much care either or it'd be more than me and Cia."

"Sounds like a depressing state of affairs. You'd think they'd try to take places of strategic importance, but I guess it's different when you're dealing with a war spanning, what, your entire galaxy?"

"Yeah it's kind of existential. But the not-important places are good practice for the actually-important places."

"Everywhere's at least a little important, if people live there," she muses. "So you guys run on magic, you said?"

"Yep! Magical girls, that's us."

"Fascinating." Maybe it's not the annoying kind of magic. "I suppose I'll get a better sense of how your powers work in practice when I see you in action. Just girls?"

"Only girls. Dunno why, but boys never get picked."

"The magic itself picks you, or...?"

"No, the Imperatrix or the Polemarch visits you and makes you magic if you're good enough. Uh, they're the leaders of the Domain and the Compact and like, really strong magical girls."

"Cool, cool." So a pair of intentional evil matriarchies, insofar as anyone involved is an evil matriarchy. Unless there's some reason the magic only ever works for girls. Diligently not making assumptions, here. "Lemme know if the questions get annoying, I know you have a lot on your mind right now."

"Nah, just gotta swat some tanks around. Oh hey, we're here." 'Here' is an apparently undistinguished intersection.

She lands a reasonable distance away from her guide, close enough to continue the conversation and far enough not to crowd her too much if she has to move around. "So. You're Domain and they're Compact." Can't exactly ask who the Axis powers are, can she. "Does the war between you have, like, a specific goal, or is the Compact just evil braineating aliens who bodysnatch your friends, or - International Relations 101 would be good right now."

"They ran away to the other side of the galaxy like three thousand years ago to start their own country and then expansion crashed us together again and now it's like an- ideological war, I think it's called." She bounces a bit, swinging her arms, limbering up.

"Ah. What's their ideology, then?"

Shrug. "That we're evil for being an empire or something? You might wanna back up a bit, those buildings are gonna collapse."

" - ah," she says, looking up at the buildings. "Cool, thanks."

She's thinking less Axis and Allies and more Carthage and Rome, maybe, at this point. Modern Carthage and Rome would be something. She's not actually sure how you stop Carthage and Rome from being at each other's throats. Good thing this is probably an academic question for her, because surely someone will reverse the portals at some point and then she'll be able to tell Oa about this and they can decide what, if anything, to do about this massive galaxy-spanning war in another dimension.

Unless they don't.

She floats up a hundred feet again, figuring this is a vantage point that gives her a better view of whatever's about to happen, and waits for the tanks to show up.

Which they do in short order. Lines of bright sparks race up the sides of the buildings and they crash into the ground, creating a wall with one gap where she stands at the intersection. The tanks pause, and then begin funneling towards the hole. She waits until the first one is almost on top of her before pulling an enormous warhammer out of nowhere and taking an underhanded swing at the front of the tank and sending it flying end over end through the air as if it were made of paper.

Pretty lanterny power set for someone who's not a lantern.

She considers pulling the guy out of the tank and decides that that'll lead to her fighting one or both sides of this war in the next ten seconds, which she just got through deciding not to do. She sticks to observation.

An explosive shell screams down and detonates directly on top of her. When the blast clears, she's standing in exactly the same spot, apparently entirely unaffected. She tosses the warhammer aside, and it vanishes as she rushes forward to punch a tank literally in half. She then jumps up and smacks the ground upon landing, creating a shockwave that bounces the two pieces into the air. A beam of light shoots out from each of her now upraised hands, clipping the floating scrap and sending them crashing down to explode.

Very impressive.

She wonders idly whether she could take her in a fight. Anneia's clearly more durable, but Karen can in theory keep her armor up, and it's deeply unclear which of them has more firepower.

She continues destroying tanks and essentially ignoring incoming fire. Occasionally a particularly heavy concentration will make her pause for a moment, but she's always right back into it afterward. In a little less than ten minutes, there are no more intact vehicles in the immediate area and the buildings have been ground into even finer rubble.

She takes one last look around, dusts her hands off, and trots back over to where the green girl is waiting.

"Why do they bother sending tanks against you, with that kind of power difference?"

"They were hoping I wouldn't be here. Or be younger or stupider or tireder."

"Could they not have retreated when they realized you weren't? I guess tanks make that hard."

"And also we kinda didn't want to, y'know, let them."

She sighs. Good old wars of attrition. 

"All right, well, I've brainstormed for five minutes and I have zero idea how to contact home, so I guess I'm waiting for them to contact me."

"That sounds like it kinda sucks!"

"Just a bit! But I daresay I'm not having the worst day out of everyone in a one-mile radius right now. D'you mind me asking - if the Compact doesn't care about this place, and you guys don't care about this place, and it's not really strategically relevant in any way, is there, like, a reason to be fighting over it? Surely you could find less lethal ways of practicing."

"Well if we just give things up without even trying that's a- bad habit? to be in. And there's only so much you can learn in theory if there's not even a little danger."

Sigh. "I guess if they're gonna go for it then you gotta defend it. Must lead to a lot of bombed-out planets, though."

"There's lots of planets. And you can always rebuild cities."

"I guess. What're the casualty numbers on something like this?"

"Usually in the thousands or so."

"Ah. Can't rebuild people. Unless I'm super mistaken about your tech level."

"Well. No."