I'm not sure about a specific one, but you can start by looking on fanfiction.net. Just search for 'Stiles is secretly famous' in the search bar. There are likely many different takes on this concept there. Some might focus more on his friendships, while others could be more about a romantic aspect of his secret famous life.
There's a fanfiction that I read a while ago where Stiles is secretly a famous singer. In this story, he has to hide his identity from his friends because he's afraid of how it will change their relationship. It's really interesting how the author explores his internal struggle between his love for music and his love for his friends. It shows his character growth as he tries to find a balance.
One common theme is the struggle to maintain a normal life. Stiles often has to deal with hiding his fame from those closest to him, like his friends and family. Another theme is the allure of the fame itself. Sometimes he's tempted by the perks of being famous, but also realizes the downsides.
His best friend could discover it. Since they are so close, they might notice something different about Stiles that makes them suspect he's actually a girl.
There is a fanfiction where Harry discovers he has a natural aptitude for potions because of some ancient magic in his bloodline. It's called 'Potions Master Harry'. In it, he starts to experiment with potions in ways no one has thought of before, creating new and powerful elixirs. This not only changes his relationship with his classmates but also makes him a target for some dark forces who want to use his skills for their own evil purposes.
There's a fanfiction called 'Secretly Yours'. In this story, Draco and Harry's secret marriage is filled with tension and love. It delves into their private moments and how they deal with the outside world's potential reactions.
One interesting Stiles fanfiction is 'Stiles' Time - Travel Trouble'. Here, Stiles gets thrown into different time periods and has to find his way back. It's a fun read as it shows Stiles in various historical settings and how he uses his modern - day knowledge to survive. There's also 'Stiles and the Forbidden Friendship' which explores an unlikely friendship Stiles forms with a character from the other side of the supernatural divide.
Well, it could be that Stiles is secretly a girl and in the fanfiction, this secret is slowly revealed as he falls in love with someone. And the person he loves starts to notice little things that don't quite add up with his supposed male identity, like his more delicate features or his different style of communication.
One popular 'Harry and Ginny secretly married fanfiction' is 'The Secret Bond'. It delves into how they managed to keep their marriage a secret from their friends and family initially. It has some really sweet moments of them navigating their new relationship status while still being part of the wizarding world.
One popular 'Harry and Draco secretly dating fanfiction' is 'The Secret Love of Harry and Draco'. It beautifully explores their relationship in a Hogwarts setting with lots of hidden moments and tender exchanges. The author does a great job of building the tension between their public personas and their private feelings.
One good Stiles - Avenger crossover is 'Stiles in the Marvel Universe'. It has an interesting plot where Stiles uses his wits from the Teen Wolf world to interact with the Avengers. Another is 'Stiles and the Avengers: An Unexpected Alliance' which shows how Stiles' unique skills could be useful to the Avengers.
Some of his friends might be really surprised. Scott, for example, might be a bit worried that Stiles' vampire obsession could lead him into dangerous situations. Lydia, on the other hand, could be more intrigued and might want to know more about the fanfiction. She might see it as an interesting intellectual pursuit.