A recent Fortnite leak revealed the next Marvel hero to be added to the game. Since the start of Season 4, Epic Games has done an excellent job of unveiling new content every few weeks, giving fans a chance at unlocking new skins and characters.
According to data miner SizzyLeaks, the next hero has been found. Based on superhero particles in-game, we have a good idea of who "Cherry" is going to be. Epic Games is obviously using the name as a placeholder for the next secret reveal and if you don't mind things being spoiled, SizzyLeaks has a pretty good idea of who it will be.
Based on the data mined information and current theories in the game, Cherry could very well be Captain Marvel. She's a popular hero, powerful and would fit the bill for the fireball ability. She seems to have some type of energy blasts that come from her hands, so the fireball might be the best way to showcase that inside of Fortnite.
Whatever the case is, Epic Games has yet to reveal the mysterious Cherry, so we'll have to stick with theorizing until they do.