“It was becoming accepted that it was a matter of when, not if, he would be offered a big movie role and move to Hollywood,” our showbiz insider continues.
But now it appears that his sister has come along and stolen his thunder.
Bindi, 24, confirmed she is voicing a character called Isla Coralton in the Marvel animated series Spidey and His Amazing Friends, and has been doing recording sessions in secret.
“Being an enormous Marvel fan, it is an honour to be part of the extraordinary world of Spidey and His Amazing Friends,” Bindi posted on Instagram, noting that Grace, 1, is a fan of the show.
The character of Isla, an oceanographer, hasn’t appeared in Marvel media before. She shares Bindi’s love of wildlife and the environment.
“It is important to empower the next generation to love our planet,” Bindi added. “To have respect for all living creatures and the environment that they call home. And I think that this series does a really, really good job at introducing those ideas.”
What Bindi didn’t mention is that her Hollywood break came as a surprise to Robert, who felt he was on track to eclipse his much-loved sister after she became a mum and seemed happy to take time off.
“It came as a bit of a rude shock that Bindi is still seen as the more bankable star largely because of the huge amounts of press she’s generated almost from birth,” our source says.
“He privately admits he’s disappointed he wasn’t also asked to voice an animation, too. That said, Robert is Bindi’s biggest fan and supporter. He just hoped this time it might be his chance.”
The rivalry might have broken any other set of siblings, but the bond the Irwin duo share is unbreakable, forged in the tragedy of losing their dad, Steve, in 2006.
“Bindi feels bad that Robert has been overshadowed, but she’s offered to coach him on his own way up the celebrity ladder,” explains our source, who says Bindi is pushing Robert to try reality TV.
“She suggested he show off his action chops by going on Survivor – he’d be a shoo-in to win!”
WATCH BELOW: Bindi Irwin's daughter recognises Steve Irwin