What if Syren made better use of her underwater advantage when Ladybug came after her alone?
Syren Sinks
Chapter 1: Sunk
Marinette and Alya slipped into the theater just in time for the opening credits of the movie, Mecha Monkey vs. Cyber Shark 3. Max, Markov, Rose. Juleka, Kim, Nino, and Alix were already there.
Both Marinette (as Ladybug) and Alya (as Rena Rouge) had been delayed, stopping a mass escape of animals from the zoo. (It was thought to be the work of terrorists, and not Hawk Moth this time). Marinette had been further delayed returning the Fox Miraculous to Master Fu, and taking time to help him work on a formula to feed the kwamis so they could grant underwater breathing to their Miraculous holders.
"Hi!" said Rose, waving at them.
"Hey!" said Nino.
"Sorry...sorry...sorry," said Marinette, aware of the glares of the movie patrons she was disturbing.
As the James-Bond-like theme began to play, the people in the seats ahead of them jumped up and ran away.
"What's going on?" asked Marinette.
In an instant she knew. Water flooded beneath them, making them all raise their feet.
"Okay, who left the faucet running?" asked Alya.
Water was pouring in from the lobby above, as well as below. Marinette realized there was only one way out.
"The stairs! Quick!" Marinette shouted. "Everyone, up on the roof!"
All of them got to the roof, where they had a view of the flooded city. Paris was deep underwater, with only roofs and floating cars visible.
"My circuits are sensitive to water," the little robot Markov told Max.
It had to be the work of an akuma villain, Marinette thought. She had to get away and transform.
"Woo-hoo!" Kim jumped into the water, laughing happily. "Come on, guys! I can teach you to swim in two seconds flat, Markov. You just put your arms like this, then you push your legs, and it's kind of like being a frog, you see. In fact, it helps to think like a frog, too, you know..."
A mermaid leaped out of the water and slammed down on Kim, forcing him below the surface.
"Kim!" cried Max.
Marinette slipped away and found a trash bin floating nearby. She grabbed a shovel that a workman had left on the roof, and pulled the bin close enough to get in. She set off in the bin, using the shovel as a paddle.
"Marinette, what are you doing?" shouted Alya from the roof.
Marinette froze for an instant. She had hoped to get away unseen.
"Umm, I'm gonna get help," said Marinette, waving awkwardly.
The action unbalanced Marinette's crude boat and she went over into the water.
She pulled herself back out and got the bin going again, saying, "I'm fine!"
Alix mumbled something sarcastic she couldn't quite hear.
Marinette didn't care – she knew she was the help that would save the day.
"Okay, we're alone," said Marinette to the kwami in her purse. "Tikki, spots on!"
She transformed to Ladybug. She always felt like dancing when she did this, but there was no chance for that in the makeshift little boat.
Ladybug took a deep breath and swam through the devastated city. There were cars floating everywhere. She was nearly swallowed by a giant catfish. As she came up for air, she realized how hard this was going to be.
She wouldn't give up. She took two more deep breaths and went down again. Luck was with her this time. She spotted the mermaid and Kim swimming together. Kim had a bubble like a diving helmet around his head. It seemed the villain had charmed him – he was going with her willingly.
"Huh! This is amazing, Syren! I can breathe underwater, just like a fish," said Kim.
"I knew you'd love it, and I've got lots of other surprises for you, you'll see..." said Syren.
Ladybug used her yo-yo to snag Kim's foot and pull him back away from her.
"Hey!" said Kim.
"My Prince!" said Syren, swimming after Kim.
Syren caught him and swam away, towing Ladybug by the yo-yo line she had attached to Kim's foot.
Ladybug was running out of air. She clung to an ornamental iron window grille to keep from being dragged deeper.
A butterfly-shaped line of light formed around the akuma victim's eyes. The mermaid nodded and charged at Ladybug. For an instant it looked like she was going to punch Ladybug out of the water, which would have been a good thing.
Instead, the mermaid punched lower, knocking the remaining breath out of Ladybug. Ladybug nearly passed out. She was helpless, choking and drowning.
The mermaid pulled the grille from the window with supernatural strength and wrapped it tightly around Ladybug's upper torso. She pulled Ladybug's right hand out through one of the circular loops in the grille, then bent the metal circle until it clamped around her wrist. Ladybug was shackled to the heavy iron weight. The mermaid reached up to her ears and took the earrings. As Ladybug detransformed, Syren let her sink.
No strength, no air, weighed down – Marinette was going to the bottom. She was going to die. Why hadn't she tried to find Chat Noir first, or gone back to Master Fu and helped him finish the underwater formula?
Kim stared as she sank. He said, "Hey! I know her. Marinette goes to my school. Don't kill her. She's nice."
Syren swam up to Marinette and caught the grille around her. She blew a large bubble of air, which she placed around her face. She bent the grille open and set Marinette free.
"Drowning you in front of Kim would make me look bad," Syren said. "I have a better idea. You can be my hostage to lure Chat Noir down here. Don't try anything. You're completely dependent on me for air.''
"I won't try anything. I surrender," said Marinette.
For the moment, Marinette was just glad to be able to breathe again. Escape plans could come later.
"You're coming with us to the swimming pool," said Syren. "I'm going make a throne for my Prince. You can help, slave."
"Yes... Mistress," said Marinette.