At the end of season 3, we saw Master Fu leave after having amnesia and saw no longer remembers what happened.Despite knowing he will have a lovely future with Marianne Lenoir, lots of people in the fandom were very despondent and saddened. 

Fu has been a principle character in  Miraculous Ladybug- we were introduced to him in the very first episode where he recognised how Adrien and Marinette would be the appropriate miraculous holders. He even witnessed the heart-felt umbrella scene, and for him not to be there when the highly anticipated reveal happens will be a shame as he was the reason why Adrien and Marinette received the miraculouses which enable them to save the day in every episode. It would be very upsetting if he wasn't there to see them together in the future, which is going to happen in the future (despite our almost-reveals and chat blanc).

Another reason why we want him back is to find out more about his backstory- the information of his past as been very limited; we know that he was selected to be guardian, was a previous miraculous holder, and he lost the peacock and butterfly miraculouses due to a stupid mistake, but we don't have any other background information about Fu. 

Marinette is juggling a lot of responsibility, and for her to carry the responsibility of the guardian is too much. Nobody expected this to happen and there are a lot of questions that have arised as to how she will be able to be a good miraculous holder when she has played a significant role in how the victims became akumatised, especially in the past season.

So please sign this petition for our beloved Master Fu to return. If this is successful, we might start a petition for the reveal to be drawn forward- we've all united thanks to a beautiful show, and hopefully we can unite together again to bring back Master Fu!