Letās talk about everyone who knows.
Identities have always been a strict topic for Marinette, because as guardian, she felt she alone had to ensure the safety of all the heroes who were entrusted with a miraculous, this included herself and Cat Noir
However, as much as Marinette had initially attempted to keep a strict hold on her rule on keeping identities a secret, there were eventually bound to be some who would learn who she and Cat Noir were. Marinette alone has always done what she could to keep others from learning she was Ladybug, however,Ā this was never foolproof as the unexpected was bound to happen. Out of all the people who came to learn about her identity, Marinette technically only ever told ONE person her secret, and that was Alya.Ā
Back in āGang of Secretsā, when Alya confronted her about what was weighing on her, Marinette had to decide if she would continue keeping her secret or take a risk. Overwhelmed with her responsibilities as Ladybug and guardian, Marinette took a risk to tell Alya her secret identity, because out of everyone in Paris, it was Alya who broke Marinetteās fears over what could happen if Hawkmoth discovered someone knew her identity. Alyaās actions in āGang of Secretsā and āSenti-bubblerā, left Marinette willing to entrust her secret, as well as a miraculous, to Alya, but most of all, it convinced Marinette to ease up on her rule to not entrust a miraculous to the people whose identities were exposed, and instead have faith her friends could protect themselves and trust they would not betray her in the same sense Chloe did, as they did not prioritize the power of the miraculous, but rather the help they could give to her and all of Paris, even without superpowers.
Now, as of season 5, including Alya, there are now 8 people who know Marinette is Ladybug, but unlike Alya, Marinette never told any of the others her secret identity, they all just found out on their own, one way or another.Ā
Luka was one of the rare few who learned both Ladybug and Cat Noirās identities, but the only reason he found out both was because he was placed in the unique situation of fighting an akumatized villain with the power to potentially expose Ladybug and cat Noirās identities. Wishmakers power transformed Ladybug and Cat Noir into physically becoming what they dreamed they wanted to be when they were kids. Normally the quantum masking magical effect of the miraculous would help confuse human minds to prevent people from connecting the obvious, so they wouldn't easily identify the heroes through appearance alone, but Wishmaker counteracted that magic by changing their entire appearance. Ladybug had hoped that by Viperion using his power of second chance, he could help them defeat Wishmaker before he got the chance to use his power on them. Unbeknownst to Ladybug, Luka felt no other choice but to lie about learning her and Cat Noirās identities, until āMigrationā, because just like Ladybug said in āEphemeralā, if anyone knew either her or Cat Noir's identity, things could still be manageable, because at least there would still be one of them left to fight shadow moth if he took action to defeat just one of them, but if anyone knew both her and Cat Noir's identities, then it's over for everyone. Luka knew that if Shadow Moth caught him, everyone would be endangered, but he did not want to become a priority for the heroes to protect over everyone else in Paris, so he kept it a secret until he had no other choice but to tell Ladybug and all of his friends he knew.
(In "Migration", Luka reveals to his friends he knows both Ladybug and Cat Noir's identities, and must leave Paris for everyone's safety, including his own.)
Luka left Paris for his and everyone else's protection, but in the season 5 finale, it was revealed that he had come into contact with SuHan and had been under the tutelage of the guardians. Luka was taught to fight by Su Han, so if he also learned how to defend himself against the akumas the same way Su-han did in āFurious Fuā, Luka may be able to return to Paris regardless of Lila being the new butterfly holder, and unlike Su-Han and the other guardians, Luka has experience fighting against akumatized villains, allowing him to defend himself better so as to not leave Ladybug and Cat Noir to worry over his safety.
(London special, Alix reviews everything she knows about Marinette and Adrien's history as Ladybug and Cat Noir)
Aside from Luka, Alix is the only other person who currently knows both Ladybug and Cat Noirās identities, but unlike Luka, Alix is the only person who can know any hero and villains identity at any given time, this was something that was inevitable because unlike the other heroes, Alixās power over time left her the responsibility of ensuring the timeline stayed safe, her job meant she had to look over the history of everyone's lives to ensure everything was on track. Such knowledge would of course place her in a great deal of danger, but fortunately, she remains at a safe distance in the burrow, traveling through time. Ladybug never told Alix her identity, but she had no complaints over Alix knowing her personal secrets, along with anyone else's, because she knew it was just part of Alixās duty as the bunny miraculous holder to one day know such secrets, secrets even she can't know, no matter how much she asks Alix.Ā
(Kagami learns Marinette is Ladybug)
Kagami was an interesting case. Marinette never told Kagami her secret identity, but in āRepresentationā, it was revealed that Kagami wound up being at the right place and time back in āPerfectionā, when she overheard Marinette talk about her identity to Alya, at Anarkaās boat, during a moment of internal struggle over her love for Adrien. Even though Kagami was akumatized that same day she discovered Marinetteās identity and then later akumatized again in āProtectionā, Kagami never told Monarch Marinetteās secret, Monarch never even sensed she was hiding such a secret like he did with Luke in āMigrationā. Of course Kagamiās crisis over her friendship with Marinette was likely what kept her mind clouded enough to prevent Monarch from sensing she was hiding something from him, but at the same time, no matter the situation, Kagami could not help but feel a sense of loyalty to the friend who was always there for her, as both Marinette and Ladybug.Ā
Even after resolving those matters and being de-akumatized, Kagami did not reveal to Marinette she knew her secret, until āRepresentationā. Kagami is normally very upfront about things, but to know the biggest secret of Marinetteās life, was likely something Kagami felt she needed time to figure out how to tell Marinette. Kagami might have been in the dark about a lot of things about Marinette, but its interesting to see her shift from the one who knew the least, to the one who now knows everything, things Marinette couldn't even bring herself to tell Alya, like the truth about Gabriel's demise.
Felix didn't know Marinette was Ladybug until Kagami told him. Kagami telling Felix Ladybug's identity made sense seeing as he was willing to confide in her one of the biggest secrets in all of Paris, Monarchās secret identity. Felix trusts Kagami with his secrets, but doing so meant more than it being just about trust, it was about him accepting that he needed help.
Felix put quite a target on his back when he blackmailed/bargained with Gabriel to give up the peacock miraculous back in āStrike backā, and although Felix refrained from using his powers to wipe Gabriel out of existence again (First time was in "Emotion"), Felix knew Gabriel still needed to be dealt with before he could bring further harm to him and everyone else in his life he wanted to protect, and who better to help than the one person Kagami knew wanted to stop Monarch more than anyone, Ladybug. So long as Felix prefers to rely on his own abilities, he has no interest in the powers an akuma can provide, allowing him to resist Monarchās control, but weāll see about Lila.
Su Han discovered Marinetteās identity with the help of a magical compass that located the miracle box. Marinette could not hide her identity from him, let alone lie to him, because the box was in her own house. Although Su-Han knows Ladybugās identity, she had refrained from letting him know Cat Noirās too. Su-Han may be capable of defending himself from the akumas and miraculous holders, but he has no real experience fighting against akumatized villains, leaving him vulnerable if it was ever revealed he knew both Ladybug and Cat Noir's identities, fortunately, he only ever visits Paris if it's necessary.
Marianne, Fu's wife, was someone who had a long history with Fu. Fu trusted Marianne with the knowledge about the existence of the miraculous and how he had the responsibility as the last guardian to protect the jewels that wielded such incredible power. Marinette didnāt need to tell Marianne her secret identity, it would have been easy enough for her to figure things out on her own.
Marianne knew that whoever wielded the miraculous, was in turn associated with Fu, so even after seeing Marinette in civilian form to reunite her with Fu at the end of āMiracle queenā, it would have been plainly obvious to her that Ladybug and the girl who escorted Fu after he lost his memories, were the same person. Marianne and Fu don't live in Paris anymore, so Marinette can feel assured they are at a safe distance fromĀ the akumas.
Nathalie discovered Marinette was Ladybug, after Gabriel finished making his wish. In the London special, after Gabriel made his wish, Nathalie was originally planning to continue her efforts in stopping Gabriel the moment she returned to the secret basement under the Agreste mansion, but she instead discovered Marinette talking to Plagg and Tikki. Nathalie heard Marinetteās conversation with the kwamis and that just about confirmed Marinette as Ladybug, even before she transformed into Bug Noir. Nathalie didnāt end up learning Cat Noir was Adrien again, but now she faces an entirely new dilemma, hiding the truth from Adrien about Marinetteās secret life as Ladybug as well as the truth about Gabriel's death. Marinette might have had her doubts about Nathalie, but knowing just how much Nathalie has been there for Adrien was enough to make her feel willing to trust her. Nathalie was normally the one who was willing to be akumatized for the sake of a mission, but now that the butterfly miraculous is in the hands of Lila, Nathalie is now just another citizen trying to avoid being akumatized.
Those are the people who currently know Ladybug and Cat Noirās identities, but let's not forget the people who knew temporarily.Ā
It's not the first time Nathalie knew one of the heroes' identities, in āCat Blancā, she saw Adrien transform into Cat Noir. However, this left her greatly conflicted about what she was doing, because she never set out to hurt Adrien. The shock of learning Adrien was Cat Noir alone made her make the mistake of telling Gabriel, who jumped at the opportunity to akumatize his own son for the chance at a quick victory. However, the events of Cat Blanc were never meant to happen and were quickly fixed by Ladybug and Bunnyx.
Lila was always hinted to be the future butterfly miraculous holder, and as soon as she got the butterfly miraculous, she wasted no time in using it to tract down Ladybugās identity on her own. Fortunately for Lila, Marinette had no idea where the butterfly miraculous went, giving Lila the element of surprise. However, Lila knowing Marinetteās identity was something that was not meant to happen, her tampering with the timeline of events to uncover Ladybugās identity only wound up alerting Bunnyx so she could do what was needed to help Ladybug prevent her from ever finding out Ladybugās identity.
Gabriel had always aimed to uncover Ladybug and Cat Noirās identities, and on several occasions, he did, even if it was only temporary. He discovered Cat Noir was Adrien in āCat Blancā, and both Ladybug and Cat Noirās in āEphemeralā. Although these moments were not meant to happen and were quickly reversed with Sass and Bunnyxās help, as it turns out, Gabriel was at most meant to discover Ladybugās identity without it completely destroying the entire timelineā¦it just had to be on the day he died.Ā
Fu of course knew both Ladybug and Cat Noirās identity because he was the one who entrusted them with the miraculous. Unfortunately, in āMiracle Queenā, in a last desperate effort to protect the miracle box, the miraculous, the Kwami, Ladybug and Cat Noir, along with himself and Marianne, he wiped his memory clean. Without his memories, Hawkmoth had little to no use for Fu.
Adrien got the chance to figure out Ladybugās identity in "Cat Blanc", but it was in āEphemeralā that Ladybug chose to learn Adrienās identity first and then later decide to reveal her own identity to him. In both episodes, the two learned each others identities, and each time they did, it led to disaster because of one crucial thing, Gabriel was still Monarch. The opportunity to obtain a quick victory had always outweighed any sense of logic Gabriel had, making him quick to use the control he had over Adrien to akumatize him and defeat Ladybug, but now that Gabriel is gone and the rings containing Adrienās amok have been returned to him, who knows what's going to happen.
Moving onto Adrien, as of season 5, only two people officially know he is Cat Noir, Luka and Alix. Adrien has not had many occurrences that led to others knowing his secret identity, because unlike Marinette, Adrien was limited by what he could do, where he could go and who he could talk to while under his fathers care, he was heavily protected and controlled in his civilian life and this alone prevented a lot of close encounters that could have led to others discovering his identity. But now that Gabriel is gone, Adrien is no longer under the same restrictions he once had, meaning anything could happen. Adrien has not told anyone his secret identity, but there are a lot of characters to think about whom Adrien could tell his secret to and even more people who could end up discovering his identity, one way or another. But again letās just wait and see what the show has to say.