
Alya Césaire is Marinette's best friend and a student at Collège Françoise Dupont. She is also the sole admin of the Ladyblog and head of the school blog. In "Lady Wifi", after Alya gets suspended from school because of Chloé, she is infected with an akuma by Hawk Moth and becomes Lady Wifi, a cellphone and wifi utilizing supervillain.
In "Sapotis", after she receives the Fox Miraculous from Ladybug, Alya, when the Miraculous is inhabited by Trixx, becomes Rena Rouge, a fox-themed superhero who helps Ladybug and Cat Noir "during particularly difficult missions" in the second season and beyond.
In "Mayura", during the fight with Scarlet Moth, Rena Rouge is Akumatized into Rena Rage, a fox-themed supervillain.
In "Oblivio" due to her and Nino's embarrassment at being caught playing the Super Penguino video game together, she, alongside Nino, are both Akumatized into Oblivio, a memory-erasing supervillain.
In "Félix", after being fooled by Félix to think that Adrien didn't appreciate his friends, she is re-Akumatized into Lady Wifi, and, along with Reflekta and Princess Fragrance, the three supervillains form the The Punishers Trio, a group of supervillains who want to get revenge on Adrien, later Félix.
In "Gang of Secrets", after Marinette keeps hiding secrets from her and the group, Alya is re-akumatized by Shadow Moth into Lady Wifi along with Reflekta, Princess Fragrance, Timebreaker, and Horrificator. The five supervillains all form the Gang of Secrets, a group of supervillains who want to reveal Marinette's secrets. However, due to being reminded of being a superhero, Alya was able to reject Shadow Moth while akumatized, which allowed her to transform back to normal. Ladybug returns the Fox Miraculous to Alya, allowing her to transform into Rena Rouge again. At the end of the episode, Marinette tells Alya that she is Ladybug.