By far the most compelling element of Miraculous: Tales of Ladybug & Cat Noir is the love square between high school students Marinette Dupain-Cheng and Adrien Agreste, each hiding their respective superhero personas: Ladybug and Cat Noir. From the series' earliest episodes, fans have been hooked into their budding romance, patiently waiting for a confession that will allow the show's main ship to officially become canon.
Interestingly, a confession -- 0r two -- occurs in Season 3, Episode 23 "Félix," but in a very unexpected way. When Marinette finally works up the courage to confess her feelings to who she thinks is Adrien, things go awry, and tension within the Agreste family thickens.
The episode opens on the one-year anniversary of Adrien's mother, Emilie's, death. To ease some of the grief, Adrien and his father Gabriel are visited by Emilie's twin sister, Amelie Graham de Vanily, and her son Félix, who bears a striking resemblance to Adrien. According to Amelie and Adrien, Félix has always been mischievous, but the recent passing of his father has made him cruel and cunning -- a complete contrast to Adrien's kind and selfless nature. Félix harbors some jealousy towards Adrien and is angered by the fact that his cousin did not attend his father's funeral as Gabriel thought it would be too hard on Adrien with the wounds from Emilie's death still fresh.
Unfortunately, Adrien's apologies do nothing to keep Félix at bay and he jumps at the chance to take advantage of his cousin's kindness. As Adrien searches for games they can play, Félix snoops around his room, stuffing Plagg's stash of camembert cheese beneath Adrien's pillow and stealing his phone. On his phone, he discovers Adrien's blatant crush on Ladybug and an encouraging video sent by all of his friends. It is within Marinette's part of the video that she confesses, even muttering the words "I love you." Unfortunately, her confession means nothing to Félix, who promptly deletes the video before Adrien can see it.
In response, Félix takes Adrien's clothes and changes his hairstyle to look exactly like Adrien's doppelganger. With his convincing new attire, Félix sends a heartless message turning down their encouragements, which allows Marinette and Adrien's classmates, Alya Césaire, Rose Lavillant and Juleka Couffaine, to be Akumatized. When Ladybug arrives to handle the matter, Félix, still pretending to be Adrien, confesses and even tries to force a kiss on her in an attempt to gain the upper hand. Ladybug is caught off guard but is quick to recognize these aggressive actions as something Adrien would never do, forcefully rejecting him.
In addition to stirring up trouble in Miraculous, Félix also wants to take back Gabriel and Emilie's matching wedding rings as they had originally belonged to the Graham de Vanily family. He tries to bargain with Hawk Moth (secretly his uncle) to get those rings in exchange for Ladybug and Cat Noir's Miraculous, but the heroic duo captures the Akuma just as the deal is made.
A fascinating piece of trivia is that Félix was originally meant to be the real Cat Noir in the original "Ladybug PV" prior to the series being made. However, he was swapped out for Adrien to create convincing chemistry between the two lead characters. The PV showcases the series in a very cutesy, 2D anime style, serving as an early draft of the CG 3D Miraculous we know today, and it's interesting to think that we almost got a competely different Cat Noir.
Though Félix's attempts to stir the pot in the episode didn't quite work out, his vengeance against Adrien and Gabriel, as well as the fact that the creators have had ideas for his character for a while, implies that he's likely to return in a later season of Miraculous. Siding neither with Paris's heroes nor Hawk Moth, Félix is truly a wild card in the Miraculous universe, acting only in his own self-interests while his familial connection to Adrien only complicates things further for the already messy family.
