An Avengers and X-Men crossover movie could happen after Disney-Fox merger. Facebook/Avengers

There are many questions that need to be answered in “Avengers 4.” The most important of which is why Tony Stark (Robert Downey Jr.) is the key to defeating Thanos (Josh Brolin). Using the time stone to win would be too obvious and not so exciting, so a new fan theory looks at another way the heroes can win. The following article contains spoilers.

The dead character will be back in the next film, there’s very little doubt about that at this point. Cast member Chris Pratt (Peter Quill) appeared to be confirming this when he said on Instagram that he will be working with Pom Klementieff (Mantis) next year on “Guardians of the Galaxy Vol. 3.”

So, how can these characters return in the next film. A theory posted on Reddit begins with the snap that ended half the life in the universe. According to the theory Thanos’ snap created another big bang event and this led to the creation of a parallel universe. Half the population of the other universe saw the rest die too.

Dr. Strange’s (Benedict Cumberbatch) plan in allowing Tony Stark to live was to make sure that there is someone with the required skill set to understand what has happened and come up with a solution.

Tony and his team can find a way to build a bridge between the two universes that have been created, and thus the characters who died with the snap of the finger will come back to get the Gauntlet and put the universe back together.

This does not mean that all dead characters will return in the next film. Only those characters who vanished after Thanos snapped his fingers may get a chance to return.

Even with all the heroes coming together, it will be a challenge to beat Thanos. After an intense fight, all the heroes could manage to do was draw a drop of blood of the villain in the previous movie.