"This thing turned you into a girl!"

"What? No, you became a guy!"

"Uh."

They stopped shouting at each other and considered the situation. They looked at each other, then at the wall. "Right, so... what does this thing do? What just happened?"

"Well, I put my key to the hole, and..." He gestured the white key, almost identical to the one Fionna had had.

"Yeah, that's what Fionna did too. And then she wasn't here, and you were..."

"So, what's this thing then?" He looked at the wall again, tapping it. The reflection on the other side, taller than him and with bunny ears, tapped back as reflections are prone to do. "I guess it'd be some sort of a weird interdimensional transporter thingy... or whatever. That's pretty weird."

More as a reflex than anything, Flame Prince too put his key to the hole, and turned.

For a brief moment, reality was ripped apart once more, after which Flame Prince was gone, replaced by a smaller, female version of him. "Nice of you to join me, FP," Finn smiled.

"Yeah..." Flame Princess looked around. "So where are we? Everything looks about the same."

"Well, based on what we saw, I'd say we are where Fionna and Cake lived."

"Huh? Who're those?"

"Uh." He stopped: he had forgotten Flame Princess had never heard of the story, or even met its writer. "Well, there was this weirdo called the Ice King - I have mentioned him - who wrote this fanfiction where me and Jake were girls, because he's really really weird. I guess you just met a girl version of me before coming through?"

She nodded.

"Yeah, that was probably Fionna. So..."

They both turned to look at the third keyhole. The mysterious blue one, whose key none had managed to lift. "That thing's the same as in our world, too."

"Yeah." She looked around, shivering from the cold. "Do you think if-"

Her question was answered, before she could even ask all of it, by a sudden blast of chill and snow. To a human it would be a cold inconvenience at worst, perhaps requiring the change of underwear later, but the same amount thrown at a fire elemental was dangerous indeed, easily fatal if not treated. She screamed and fell down, extinguished.

"Flame Princess!" Ever the hero, Finn drew his sword and rushed at her, making sure she was all right, eyes darting around the room and alert for danger. But though it was his eyes that were expecting for trouble, it was the ears that first detected it: cold, feminine laughter, echoing across the room, as the creature came from the shadows and descended towards them.

He looked at it, and blinked. "...Betty?"

"Who?", Ice Queen asked.

"Nevermind." He drew his sword and charged at her, screaming. She just froze his feet to the ground, trapping him in place.

"So nice to finally meet you, Finn," she spoke, in an almost kindly voice, though her smile still had something unnerving about it.

"Huh? ...Wait, are you as crazy about your fanfiction than Ice King? What is even going on around here?"

"It's not just fanfiction!" Her smile turned into a snarl of anger. "It's something greater. It's a goal, a truth, a... something I'm at last achieving! It's..." She saw the human boy looking at her, confused: Flame Princess was still unconscious. "...You want me to explain? Is it okay?"

He nodded.

"It'll be pretty wordy again."

"Just lay it down on me," Finn said, stopping to hack away the ice trapping his feet for a bit. "This is really confusing and I want to know what's happening."

"Okay. If you want to. I'll try to be brief." She nodded. "This place is a portal to another dimension. But it's not a very good portal: it can't transport anyone anywhere if their home universe has a pretty good grasp of them. Which is most of the time. But not," she grinned, "if there were two of them! If they made some big Choice and caused a displacement in time, that split them in two timelines, then there'd be one too many and the gate could function for them! Get it?"

"Uh... no." He looked just as confused as before. "I mean, there's been some talk about this time disconnect or whatever, in the last dungeon and all... but I dunno. You'd think I would know about it."

"You cannot, because the two copies can never exist in the same place. So..." Ice Queen nodded. "...You made a big Choice today. Can you remember what it was?"

"Uh. No?"

"It was when you didn't go and close the window upstairs."

"...That's it? That would have taken like ten seconds!"

"Sometimes that is all it takes!" She cackled. "You see, it was I that opened the window and made a bit of noise." They looked at her. "Well okay, for you it was the Ice King," she corrected herself. "But I did it for Fionna and Flame Prince. At the same time, I got stuck in the same time displacement, meaning there are now two Ice Queens running around."

"O-kay..." He still did not quite seem to understand all of it. But he was kind of an idiot, and too young to figure most of these things. "So what was the point of all this?"

"What do you think?" Her smile went all the wider. "Now I can finally go to the world where I belong, where my beloved Finn is waiting for me! And at the same time, Ice King can come to this side and be with the Fionna he so much adores!"

Finn looked disgusted, but managed to swallow it. "Uh... I kind of already have a-"

"Just stay there for a while!" She no longer listened to him, but swooped past him and towards the wall, the light-blue frozen key at hand. "The other me will arrive soon: she's so looking forward to meet you...!" And she laughed as she turned the key in its hole, and reality buckled once more.

The laughter turned into a rather more masculine one, and quite a bit more pathetic.

"Ice King!" Finn growled at the bearded old weirdo that appeared. He was smiling happily.

"Oh hi, Finn! Don't mind me, I was just heading upstairs to meet Fionna. Wait here for a bit for your dream lady to arrive, all right?"

Finn gagged. "Look, I already have a-"

"Yeah, that's awesome, see you later!" He flew past him, beard fluttering, and up the stairs.

Finn was left alone for about three seconds, which he spent desperately hacking at the ice, and looking at Flame Princess for any signs of life and recovery. On the fourth second, another Ice Queen arrived.

"Hell-ooo, Finn!" She was attempting a youthful, seductive voice, but mostly she just ended up sounding really creepy.

"This is really messed up, you know that?" She did not seem to listen, instead preferring to come over and wrap her arms around him. It was like hugging a snowman: kind of soft, but really frigid.

He realized she was trying to smooch him, and turned away and pushed her back. "I keep telling you, I have a-"

"Oh, finally we can be together, my love! Come to me, and let us embrace until the end of ti-" She was cut off and replaced by a hideous scream of pain and surprise, and the heavy smell of burning hair.

"Stay away from my boyfriend, you hag!"

Flame Princess had come to. It was not entirely certain if she had been aiming at Ice Queen's tiara and missed, or was simply trying to hurt her face, but the end results were the same: an angry older woman preparing to hurl ice at a young girl.

It suddenly got pretty warm, as Flame Princess, probably reflexively, heat up the entire room as she prepared to defend herself. Thankfully, it was just the thing needed to negate Ice Queen's power. Before they could try and deal with it by clawing at each other's faces or whatever girls do when they fight, Finn knocked her out with the flat of his blade.

Flame Princess freed him with a simple fire, that melt away the ice from around his feet. "Can we go now, Finn? I don't think I much like this place."

"We need to go and pick up Ice King first."


Meanwhile, the Candy Kingdom was getting uncomfortably hot. According to the calculations, the power plant was now generating heat with more energy than three suns. It said something about its builder's genius intellect that it could still withstand such power.

"Oh my goodness!", Prince Gumball exclaimed. "I wonder what Fionna and Flame Prince are doing?"


Whatever Fionna and Flame Prince were doing, in the privacy of the tree house, was derailed by a knock on the door. "Go away!", she shouted from the bedroom. "We're trying to have a moment here!"

The door opened anyway. "But it's me, Ice King! The love of your life, finally reunited with you!"

"...What?"

Fionna came downstairs, her clothes kind of ruffled-up and poorly-fit, to inspect the intruder. She tilted her head, confused. "...Simon?"

"Who?"

"Nevermind. Seriously, could you leave? We can fight tomorrow."

"Why would I want to fight you, my love? I have waited for so long to get to you, and now at last I am here!" He sounded incredibly pathetic.

"...What." While she just looked at him, confused and disgusted, Flame Prince walked into the discussion. "Uh... what's going on here?"

"This weirdo thinks we're a couple."

"Oh." He looked at Ice King. "...Seriously? Why would he even-" Thankfully he was a human now, so the ensuing blast of ice, burying him in his entirety, was not as deadly as it could have been. It still caused quite a scare, though.

"Shush, adults are talking."

"Hey!" She snarled at the old man, picking up the first thing she could. It was BMO.

"All right, it looks like you are a little emotional from seeing me at last, it can happen." He raised his hands defensively. "I'll just come back tomorrow, all right? Then we can go on a date? How about a goodbye kiss before I go?" He puckered his lips.

She threw BMO at him and knocked him out cold.

The house went silent for a few seconds, after which Finn arrived. "Oh. Hey, you dealt with him pretty well by yourself." He smiled. "I was a little worried, but it looks like I can beat up evil just as well as a girl."

The two human heroes examined each other, and found that all was well. "You look pretty cute."

"Don't you start that too," Finn groaned. "I already had to deal with a witch thinking that. Also I have a girlfriend."

"Hey, so do I," she defended herself, then stopped when he raised an eyebrow and looked amused. "Uh, I mean, boyfriend. He's over there in the ice. I'm just saying, you're cute. I am allowed to say that."

"Well, thanks." He tried to pick up Ice King, who was pretty heavy. "Ugh, now I will have to drag this weirdo back... this is going to take a while."

"I can help." She came to help him. "I guess your girlfriend can melt down my boyfriend in the meantime?"

"Sure," Flame Princess said, moving inside. "I'll join you at the cave later."

"All right." Fionna grinned at Finn. "Well, looks like the day was saved just fine. High-five!"

They high-fived. And simultaneously, in the world of Ooo, another set of Finn and Fionna high-fived over the unconscious body of the Ice Queen that had crossed over to their world. It was the most awesome high-five either world would ever see.

It was also the last.

Bodies displaced in space and time are dangerously unstable. When split in half, one half tossed over to another world, and touching at the other, gender-swapped half, it results in a backlash of an explosion, powerful enough to incinerate the entire planet and turn it into a burned, lifeless husk. On both the world of Ooo and the world of Aaa, the burning nuclear energy swept over the lands and destroyed everything, all the poor unexpected inhabitants and their houses, the forests and mountains, all was turned to dust.

Then everyone died. The end.