The Russo brothers were convinced they'd never return to the Marvel Cinematic Universe.Siblings Joe and Anthony Russo are returning to the franchise to direct Avengers: Doomsday and Avengers: Secret Wars, but it wasnt in their original plans as they thought they were ready for new challenges after helming 2019s Avengers: Endgame, their fourth film in the comic book world.Joe Russo told RadioTimes.com: I mean, we were very tired after those last movies, we did four of them in seven years. It was a lot of work, and we were asked a few times, and we said no.Anthony Russo added: The work that we'd done in the MCU was really among the most fulfilling of our lives. We were able to tell a four movie narrative arc that was very interconnected and built... you know, each sort of expression built on the previous.But the directors felt compelled to return after finding a new story to tell in the MCU.Anthony said: We're excited to come back now, because we've been away for a bit, were excited to sort of pick that narrative through line up again that we were carrying, and find a new way to push it forward with everything that's transpired since that point in time.Its a challenge, but it's one that we think we finally lit on an idea that we felt really made it work ... really made it worth us coming back to tell another story, so we cant talk about it in much detail sorry, but were excited.Getty ImagesGetty Imagesloading...READ MORE: Every MCU Movie Ranked From Worst to BestJoe added: We finally, as Ant said, found a story that really excited us, [that] we felt compelled to tell over other stories that we've been working on, and so now were back.And Anthony teased that fans wont be disappointed.He said: If you like the work that we had done previously in the MCU, I think you should be excited for what we've got coming.Doomsday will see Robert Downey Jr., whose previous MCU character, Tony Stark/ Iron Man was killed off in Avengers: Endgame,return to the franchise as the villain Doctor Doom, and the Russos recently told how he has been working hard on developing his new alter ego.Speaking to Entertainment Tonight, Joe Russo said: Its a very intense process developing the character. Hes so immersed in it. He is so dialed in.Anthony added: Thats the kind of artist he is. Thats the kind of actor he is.Get our free mobile appMovies That Were Originally Supposed to Have Much Darker EndingsThese movies were originally intended to end on down notes. Somewhere along the way, that definitely changed...Filed Under: Avengers: Doomsday, Marvel, Marvel Cinematic Universe, Russo BrothersCategories: Movie News, Superheroes