Sharkboy and Lavagirl weren’t originally supposed to be in We Can Be Heroes

Rodriguez, whose other credits include Spy Kids and Sin City, has explained that his new movie started life as a standalone original feature before he decided to add in the characters from his previous film later in the process.

Speaking to RadioTimes.com ahead of the film's streaming debut, he said, "I wasn't really returning to that universe [of Sharkboy and Lavagirl], I just made those characters fit into this universe. Because We Can Be Heroes is a new universe for me, and it's a new story and script.

"It was for Netflix and they asked me to make a new family film for them because they loved Spy Kids, they loved Sharkboy, they work really well on their service – and they wanted something original so I came up with this original story."

He added, "So in the original script, they weren't in there because I wanted to deliver an original story and then once that was done, I said 'I would love to try and borrow from the other studio, the characters of Sharkboy and Lavagirl’ and so I put them on the adult team [thinking] that will help legitimise the adult team.

"Because there will be two characters at least that you've heard of for 15 years – even if you never saw those movies, in pop culture you know of Sharkboy and Lavagirl."

The filmmaker admitted that at least part of the appeal of including his former characters related to being able to use their powers again in the creation of another character.

One of the main young superheroes in the new film is Guppy, played by eight-year-old Bird Box star Vivien Lyra Blair, who is the child of Sharkboy and Lavagirl and therefore combines both of their superpowers.

"Selfishly I could then have a little kid who's got both powers in one, because they are incredible powers," Rodriguez explained. "And as I was coming up with new kids with new powers, I wished I could give one shark strength because that was cool about Sharkboy or give you the power to manipulate liquids and lava.

"So borrowing them for the parents allowed me to create a little super kid like Guppy – who's just incredible!"

Interestingly, while original actress Taylor Dooley has returned as Lavagirl, Taylor Lautner was unavailable to reprise his role as Sharkboy from the 2005 film, with the part instead played by JJ Dashnaw in a silent cameo.

We Can Be Heroes is available to stream on Netflix from Christmas Day 2020. Looking for something else to watch? Check out our guide to the best series on Netflix and best movies on Netflix, or visit our TV Guide