A beautiful spring sun lit up the Place de Vosges, the park near the Dupain-Cheng bakery. Two small children, a brother and sister played in the grass. The brother, Charlie, wore a green tutu, gold crown, and had declared himself ruler of the park. His sister, Claire, wore cardboard armor and brandished a matching sword.
"I'll be your captain of the guard!" She said in her toughest voice.
"Let me see your sword." Charlie used it to tap both of his sister's shoulders. "I knight thee, Sir Claire! My captain of the guard!"
Claire laughed and took her sword back.
"Let's go get that dragon!" The siblings ran off after an imaginary dragon. Unfortunately, they weren't looking where they were going, and ran straight into a tall, skinny man.
"Well, well, well, what do we have here?" The man asked good-naturedly. "A princess and her knight?"
"No!" Charlie exclaimed. "I'm not a princess! I'm a king!"
"Oh, my mistake," the man said. He shook his head and walked away. Charlie and Claire played a little longer, until their mother called for the twins. Their imaginary dragon followed and they fought it while they ran to Mom.
"Come on, Claire, we need to get you to dance lessons," Mom said, taking Charlie by the hand. Claire stomped her foot.
"That's Charlie! I'm Claire."
"Oh, right, you two switched costumes today," Mom said. "Well, come on! We don't want to be late!"
Charlie and Claire pouted during the car ride to the dance studio. It wasn't that hard to tell them apart! But even Mom mixed them up! A dark black butterfly landed on Charlie's crown. The glowing butterfly symbol belonging to Shadowmoth appeared in front of both children's eyes.
"Exchangers." Shadowmoth's deep voice sounded like it was right in front of them. "You're so tired of people mixing you up, so I'm giving you the power to mix them up! All you have to do in return is give me Ladybug and Chat Noir's miraculous."
"Yes, Shadowmoth," they said in unison.
At the swimming pool, swim team tryouts were being held. The coach, Ms. Dubois, paced up and down the line of students in front of her. She wore a black swimsuit top, billowing blue swim shorts, and a very tight swim cap. The combination looked ridiculous on her bony frame. She peered down her angular nose at Adrien Agreste.
"Agreste." Ms. Dubois' nasally voice was not fun to listen to. "Let's see what you've got."
Adrien nodded once, and assumed his position on the diving board. Just as he was about to jump, a cackling, green-faced king flew over the glass ceiling. Adrien began backing down the diving board.
"Um, Ms. Dubois, I need to–"
"You don't need to do anything other than dive!"
Marinette tried making an excuse to leave as well.
"Ms. Dubois, I really need to use the restroom…"
"No one is leaving until tryouts are over!"
Marinette put her head in her hands. Alya placed a hand on her best friend's back and tried to convince Ms. Dubois to let her leave.
"I think Marinette really has to–"
Ms. Dubois interrupted her with another refusal. Alya gave Marinette a shrug. There was nothing more she could do. Adrien performed a perfect flip off the diving board and tried to leave again. Ms. Dubois stopped him again.
"I said, no one is leaving until tryouts are over."
Marinette hit her head against the wall, repeatedly. Eventually, she gave up and just waited for everyone to finish. They didn't get a chance to, however, because a blue-faced knight crashed through the ceiling.
"I am Captain Exchanger! No one is going to mix up King Exchanger with me any more, but you'll all be mixed up!"
Before anyone could do anything, Captain Exchanger swept her sword through the air. A blast of light hit the students. Adrien slipped when it hit and crashed into Marinette. When he looked up, he jerked back in surprise. He thought he had landed on Marinette, but the person below him was a boy with short, dark hair.
"Oh, sorry," Adrien said. That was weird. His voice was unnaturally high. Then he noticed the long, blonde hair hanging on the sides of his face.
"A-adrien?" The boy asked.
"Wait…Marinette?"
Confused conversations started up around them. Everyone was now the opposite gender. Alya was a guy, Nino a girl. Some students panicked, others shrugged. Most were just grateful that Ms. Dubois had required everyone to wear wetsuits for tryouts. Ms. Dubois herself, or rather himself, was still just as bony but had broader shoulders now.
"Well, everyone," Ms. Dubois said. Her voice was still nasally. "I suppose this qualifies you all to leave. But you had better be back here at the same time tomorrow!"
Everyone scrambled to get home. Marinette ducked into the locker room to transform.
"Tikki, spots on!"
It felt good to be in her super suit, even if she wasn't the same. The knight flew past the window, so Ladybug followed. Three streets over, Chat Noir found her.
"Ladybug?"
"Chat Noir?"
"The one and only!" Ladybug almost couldn't believe that the girl in front of her was Chat Noir. The suit was the same, but Chat Noir himself was now herself. "Well, m'lady, I guess you're m'lord now."
"I guess you should call me Mr. Bug. Wait, no, that was you. I'll be…Sir Bug."
"And I'll be Chat Noire."
"All right, then, Chat Noire. Let's get this akuma."
And off they went. Captain Exchanger found them first. She attacked Chat Noire with a slash of her sword. Sir Bug used his yo-yo to trap her.
"Chat Noire, cataclysm her sword!"
Chat Noire did as she was told, and to no avail. No akuma came out of the broken sword. Captain Exchanger cackled.
"The akuma isn't there. I must protect my king!" Captain Exchanger fizzled into nothing.
"No!" Sir Bug growled. "We had it! We had to have it."
"Maybe the akuma is in King Exchanger's crown," suggested Chat Noire. "I'll go recharge my kwami and meet back up with you."
"All right."
Twenty minutes later, they met again. They began brainstorming ideas for where King Exchanger might be hiding. Perhaps the school? No, probably not. Maybe the Louvre? No. Then Sir Bug figured it out.
"They'll be at the Eiffel Tower!"
"Why the Eiffel Tower?" Chat Noire asked. "What about a castle?"
"They're kids," Sir Bug explained, "which means that they'll probably find the tallest tower around, which is the Eiffel Tower!"
"Of course!"
A few minutes later, Sir Bug and Chat Noire arrived at the Eiffel Tower. A glowing orb surrounded the tip as they got close. Sir Bug's yo-yo bounced right off when he tried swinging up to it. He shook his head.
"It's a force field."
"Oh no, what a cat-tastrophe!"
Sir Bug gave Chat Noire and unamused look. Chat Noire grinned. Sir Bug decided to move things along before Chat Noire could make another terrible pun.
"Lucky Charm!"
The charm gave them a cardboard sword.
"What are you supposed to do with that?"
Sir Bug hmmed. He looked around, and the only things that lit up with the 'ladybug vision' were the two kids. He smiled. He knew just what to do.
"Chat Noire, we're going to play make believe."
"Sounds fan-cat-stic."
"You're better at puns when you're a guy."
"You're no fun."
The superheroes got as close to the glowing orb as they could, then faced each other.
"Aha, Sir Bug, we meet again!" Chat Noire brandished her staff.
"Muahaha, you'll never beat me, Chat Noire!"
Two heads poked through the force field.
"What are you doing?" Captain Exchanger asked. Shadowmoth interjected with a 'get the miraculouses,' but they ignored him.
"I'm the warrior princess Chat Noire! And this is my nemesis, Sir Bug!"
"Can we play?!" King Exchanger asked.
"Yeah, come on down," Sir Bug yelled.
The supervillains came to the superheroes' level. Captain Exchanger leapt into action next to Chat Noire. They battled Sir Bug, until Sir Bug impaled Chat Noire.
"Oh no, you got me!" Chat Noire feigned death. "Go get him, Captain."
"I will avenge you!"
King Exchanger drew close to Chat Noire. The superhero whispered the word 'cataclysm.'
"Are you dead?" King Exchanger whispered.
"Nope," Chat Noire replied, placing her hand on King's crown. It broke and the akuma fluttered out. Sir Bug used his yo-yo to de-evilize it.
"Bye-bye, little butterfly. Miraculous Sir Bug!"
The lucky charm changed everyone back and fixed what had been broken. Ladybug sighed happily after dropping the kids off with their mom.
"I'm glad to be back to normal."
"Me too," Chat Noir said. "Being a girl was fine and all, but I like being me."
"I like you being you, too."
With that, Ladybug yo-yoed off, leaving a speechless Chat Noir on the Paris rooftops.