Chapter 3 begins from Giselle Winters-Blanchet's point of view. She's an all new character from Mr. Haprele's class (which is the same class Marc is in. As well as Kagami). She's walking a street with an address in hand, looking for something, constantly pulling on her shirt sleeve to hide and then reveal her bracelet. She actually winds up right outside Master Fu's acupuncture clinic. However, Giselle is clearly disappointed and confused as the address she has, his address, is supposed to be a jeweler. She searches the street, but there's no jeweler to be found. Frustrated, Giselle resigns and heads to school.
During lunch time, Giselle stays back a bit and helps Mr. Haprele. She smiles though there's a hint of fakeness to it though most people see her as just overly helpful. She's kind of seen as "everyone's big sister." Her mind plays over and over take initiative. Mr. Haprele asks her if she's okay, and it's pretty clear he's alluding to the fact her mother recently passed away. Giselle says she's fine, and it's clear she won't ask for help. It's hinted her bracelet belonged to her mother. Mentally, she has a fear of "being a burden."
Because of her time helping Mr. Haprele, Giselle is one of the last to lunch. She looks for her friends, Meera Pugliese and Raissa Deschamps. However, it turns out Meera is absent (she's in Class C whereas Giselle and Raissa are in Class B), and Raissa's table is already full. Not wanting to cause problems or burden the people sitting there, Giselle looks elsewhere for somewhere to eat.
With most of the seats taken, she winds up sitting down next to Marc Anciel, who is buried in his writing. This has happened before. However, this time Nathaniel Kurtzberg joins them, much to Giselle's surprise. She learns they're co-opting Nathaniel's web comic, and Giselle is thrilled because she's a fan of it. Nathaniel thanks her for the compliment, and Marc replies shyly. Two girls in Giselle and Marc's class, Marie Chauveau and Suzette Rault, walk by and giggle. Marc is clearly uncomfortable with the attention, but Nathaniel tells him to ignore them. They work on planning their story. Nathaniel drops some hints about "another superhero," but overall he and Marc decide to keep The Mighty Illustrator as the co-protagonist. It also slips out a bit that Nathaniel is torn between Ladybug and Marinette. At one point, they ask Giselle for advice about the female perspective and voice. Giselle tells them women are not one single group, everyone is unique, so they need to make their characters unique too. Marc and Nathaniel ask but does this sound like a girl. Giselle reviews it for them. Again, it's a sample of how she always pushes herself to help other people.
Background needs to mention that Adrien Agreste invited Kagami Tsurugi and Marinette Dupin-Cheng invited Luka Couffaine to the ice rink, as that double date is still canon to this fic too.
After school that day, Giselle Winters-Blanchet again sticks around to help. A passing mention goes to some of her other classmates, including Kagami Tsurugi and Tsuyu Asui (the latter is borrowed from My Hero Academia). Because of this, Giselle is late in going home. She heads for the nearest subway, only to find the line she usually takes has been shut down due to Jagged Stone filming a music video there.
Without enough money for a taxi, Giselle only has two choices to get home: walk or call her dad. She debates about calling her dad, but the phrase it's an inconvenience echoes in her head. She puts her phone away and begins walking.
Partway home, Giselle notices an akuma butterfly flying in the sky. She ducks out of sight, heart beating, but it isn't targeting her. Remembering the new app, Akuma Alert, Giselle pulls out her phone and snaps a picture of the butterfly. She quickly uploads the image into the Akuma Alert app, pinning its location via GPS. This notifies everyone else with the same app that an akuma has been spotted, and they need to evacuate the area (and remain calm, so they don't get akumatized themselves.)
Giselle debates about hightailing it, but she realizes that if the butterfly hasn't noticed her, she can keep track of its movements. So she tails the butterfly, uploading its location in real time GPS. She follows it at a distance until it reaches the ice rink, where Giselle loses sight of it due to street traffic.
A moment later, Philipe gets akumatized into Frozer (it's assuming the readers know what happened as they know the canon episode). The area around the rink freezes over. Cat Noir and Ladybug show up with their new ice-based transformations. However, Frozer expands the area that's frozen. People try to flee but wound up turned into ice statues where they are.
Giselle, still hidden, also turns to flee. However, she gets boxed in as both sections of the street get frozen with the ice closing in on her. She panics, closes her eyes, and braces for the inevitable. Her bracelet activates, transforming her into a snow leopard based superhero. In her case, this is because of the nearby element of ice combined with her negative feelings of insecurity.
Her outfit is a fuzzy snow leopard pattern unitard with furry cuffs, gloves, a tail, and ice skates. Her mask is also a standard spotted domino mask, and she has cat ears. Her hair has been twisted into a braid and frosted, so it looks lighter than her natural hair color; it also has several snowflake studs adorning it. Her weapon is a ribbon dancer stick, which she can also use to web-sling much like Ladybug and Spider-man.
Giselle is stunned by her transformation and studies herself. She's the only one standing amid a frozen street, everyone else trapped. She hears the sounds of Ladybug and Cat Noir fighting Frozer, makes up her mind, and skates in to join the fight. She realizes she feels far more confident now than she does when she's not transformed.
Ladybug and Cat Noir are shocked to see another superhero. Ladybug asks her where she came from; Giselle admits she doesn't know. Ladybug quickly, mentally runs through the known miraculous, but there isn't a snow leopard. Cat Noir asks her her name. Giselle, being closer to Cat Noir than she ever has been before, goes instantly tongue tied when she realizes he's cute. It's instant crush; she even sees him with bishounen sparkles.
Cat Noir asks if "the cat has her tongue," to which Giselle giggles, much to Ladybug and Cat Noir's surprise. Giselle likes Cat Noir's puns. She then says she's…Snow Leopard. And immediately berates herself for such an uncreative heroine name.
With Frozer still putting pressure on them, they turn their attention to the matter at hand. Much to their surprise, Snow Leopard can keep up with him. Using Snow's speed, Ladybug and Cat Noir are able to corner and de-akumatize Frozer (it should go without saying this also includes use of Lucky Charm and Cataclysm). Purify the akuma, world-healing wave, Pound It, the usual.
Ladybug has a ton of questions for Snow, but the beeping on her earring stops her from getting answers. Snow doesn't understand the time limit, but both Ladybug and Cat Noir hustle off. That leaves Snow alone, and she realizes she has no idea how to de-transform. She remains hidden, trying to calm herself down, as it wears off on its own.
This results in her getting home late. Her dad asks her where she was. She lies and says she was at the library studying, as she doesn't want to admit that she decided to walk rather than call him for help and that she can't admit she turned into Snow. Giselle goes to her room, flops on her bed, and studies her mother's bracelet. She knows it has something to do with what just happened. But what? She feels anxious.
Meanwhile, Marinette goes to Master Fu that evening to report what she saw about Snow. Master Fu is flummoxed, as he knows Marinette is right and there is no snow leopard miraculous. At least no snow leopard in this miraculous box—there are three more boxes, one for each hemisphere. But this is only a hint at the greater world lore, and Master Fu is fairly certain none of those have a snow leopard either. Marinette asks him if it's an akuma or something (an amok?), but Master Fu says it doesn't feel like that either—it feels older. He does a head count of all his miraculous just to be sure, and they're all accounted for. Wayzz and Tikki have no helpful information either.
Master Fu flips through the digital book he made from the physical grimoire they stole from Gabriel Agreste—no information. Marinette also mentions the oddity that happened while they fought Reverser. She and Cat Noir heard a wolf's howl, and then their miraculous recharged. Master Fu said he's going to look into every resource he can find, but for now she and Cat Noir have to be extra careful. This could be a plan of Hawk Moth…or someone else.
It cuts to Hawk Moth, who now has absolute proof that there are more heroes in Paris. He wants their miraculous, of course, if those are even miraculous. However, he can sense something very different about these new heroes. Something about them and their powers that reminds him of…his own powers.
To be continued in Chapter 4: Crow-man…