After he exited “The Matrix” trilogy, and before he entered the gritty world of “John Wick,” Keanu Reeves’ bid to lead another franchise as DC-Vertigo Comics’ supernatural antihero John Constantine fell short.

Now, going on 16 years after “Constantine” was released, the screenwriter of the 2005 big-screen adventure is revealing what he might have been for Reeves’ iteration of Constantine. In a Reddit AMA appropriately titled, “How I wrote Constantine: A Journey to Hell and Back,” scribe Frank Cappello said if the original film had been more successful, Reeves’ exorcist-slash-demon hunter character could have made a second film appearance — and with another DC icon, to boot.

“After ‘Constantine’ released and didn’t do as well as the studio wanted, they had to cancel my contract on writing an official ‘Constantine 2,’” Cappello said in a Reddit AMA. “They offered me two alternates and one was Swamp Thing. Now if you know the Constantine/Hellblazer world, Alan Moore wrote the original Swamp Thing and that was where John Constantine was first seen. So once I saw that I decided to pick Swamp Thing to write.”

While the worldwide box office numbers for “Constantine” look solid on paper — the film earned $221 million worldwide against a $75 million budget — the tally wasn’t enough for Warner Bros. to justify another movie with Reeves’ Constantine. But, as Frank Cappello revealed in his Reddit AMA, other issues prevented his vision of another “Constantine” project with Reeves from materializing.

Cappello’s Swamp Thing-Constantine script had an Alan Moore vibe

Warner Bros.

In his Reddit AMA — which was detailed in depth in an accompanying 44-minute video — Frank Cappello said he wrote the project as a metaphysical horror film, but when legal issues derailed those plans, he was forced to make some changes that effectively eliminated Keanu Reeves from the equation. “So I invented a character that had the same vibe as JC and called him Mr ‘E’. That was a Joel Silver production and it never got made,” Capello wrote. “Probably because Mr Silver wanted a giant talking plant man like the cheesy TV series and my draft was based on the darker cool world that Alan Moore originally did. I wish I could leak that script out so people could see how cool that film would have been.”

Ironically, “Swamp Thing” did eventually become a TV series that ran for one 10-episode season on The CW in 2019. “Constantine,” meanwhile, was resurrected by NBC for a 13-episode run that ran for one season from 2014 to 2015 with Matt Ryan in the title role.

While Cappello’s plans for any more “Constantine” projects appear all but dead, a follow-up by the original film’s director, Francis Lawrence, is still in the works. The “Constantine 2” director confirmed the status of the Reeves sequel in November 2023 and said plans for the movie weren’t affected by Warner Bros. DC Film and TV co-head James Gunn taking over the DC Universe. However, rights issues continue to hold up the “Constantine” sequel.