The fight between Godzilla and Kong has been years in the making, and behind the scenes, there was some uncertainty on when or if it could happen.

Godzilla vs. Kong co-writer Max Borenstein reveals when Legendary decided to make King Kong part of the MonsterVerse. Godzilla and King Kong had previously faced off in 1962’s King Kong vs. Godzilla, and the two legendary titans were given the big screen remake treatment with the advances in visual effects with 1998’s Godzilla and 2005 King Kong. Yet the status of the two ever meeting in another showdown seemed unlikely due to the complicated rights of the two characters.

Kong: Skull Island was originally developed over at Universal Pictures, who owned the rights to King Kong and had made the 2005 remake directed by Peter Jackson. Legendary Pictures had recently signed a partnership deal with Universal Pictures after their longstanding deal with Warner Bros. ended. However, it appeared in 2015 Kong: Skull Island moved from being a Universal Pictures and Legendary Pictures project to Warner Bros. With the recent release of Godzilla in 2014 Warner Bros. and Legendary Pictures announced in October of 2015 an official date was set for Godzilla vs. Kong.

In a recent interview with CinemaBlend, screenwriter Borenstein revealed that bringing Kong into the MonsterVerse came during the post-production phase on Godzilla. Borenstein is a co-writer on both Godzilla vs. Kong and Godzilla tells how while the idea was to hopefully build to Kong they waited till after Godzilla was a hit. Thomas Tull, the former CEO of Legendary Pictures was the driving force behind uniting Godzilla and Kong in a movie together. Borenstein said:

"Well, early on, during production of the first Godzilla, maybe when we were in postproduction, is when I first spoke to the head of Legendary at the time, Thomas Tull, and producer Mary Parent and Alex Garcia, who’s the executive who’s been in charge of the franchise since then, about this idea of doing a Kong film, and Thomas’ vision, because he’s a huge fan of big monsters and Godzilla and Kong, was to eventually build toward Godzilla vs. Kong. [Those were the] sort of adventures he had in mind to bring about, but it was sort of one step at a time. I only became aware of that once we were like, ‘Ok, Godzilla turned out pretty well, so let’s aim for a Kong movie, and here’s why we want to bring them together."

When Godzilla opened in 2014, the cinematic universe was still a relatively new thing. Aside from the MCU, no other studio had really tried or succeeded. Universal Pictures’ Dark Universe was barely a glimmer in the studio’s eyes and the Sony Spider-Man plans were put into doubt after the box office disappointment of The Amazing Spider-Man 2. The DCEU had started the previous year before with Man of Steel, but that film was made before The Avengers opened so the film focused on making a standalone Superman story with the cinematic universe building in Batman V Superman Dawn of Justice being two years away.

Had Kong not come to the MonsterVerse, the future for Godzilla could have been very different. Godzilla: King of the Monsters was announced before the plans for Kong were made so the studio had already set in motion bringing in other classic Toho monsters like Rodan, Mothra, and King Ghidorah. Legendary Pictures and Warner Bros. did seem to be betting big on Kaiju films, as in 2013 they had released Pacific Rim. Steven S. DeKnight, the director of Pacific Rim 2 even confirmed that he hoped for a Pacific Rim crossover with Godzilla vs. Kong. If Kong hadn’t joined the cinematic universe, one wonders if the original plan was to have a group of Jaeger pilots fight against Godzilla in a crossover film.