Robert Downey Jr's show-stopping line from 'Avengers: Endgame' was added at the last minute

Spoilers lie ahead for Avengers: Endgame…

It seemed brilliantly appropriate – if heartbreakingly tragic – that Tony Stark had the last word over Thanos in Avengers: Endgame.

After all, he kicked off the MCU as we know in back in 2008, some 22 movies ago, so he was quite rightly the person to end it.

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As Thanos tries to finish the job he started, he utters the grandstanding line ‘I am inevitable’, before clicking his fingers to find that Robert Downey Jr’s Iron Man has pinched the Infinity Stones from him.

In a dazzling case of oneupmanship, Stark quips back ‘And I am Iron Man’, before turning Thanos and his hoards into dust.

But while it seems completely natural, it seems that devising that quip proved a massive struggle for the filmmakers.

In a Q&A with directors the Russo Brothers in Washington (via Slashfilm), they revealed the story behind it, and how it was added at the last minute.

“Tony used to not say anything in that moment. And we were in the editing room going, ‘He has to say something. This a character who has lived and died by quips.’ And we just couldn’t, we tried a million different last lines.

“Thanos was saying I am inevitable.’ And our editor Jeff Ford, who’s been with us all four movies and is an amazing storyteller, said ‘Why don’t we just go full circle with it and say I am Iron Man.’ And we’re like, ‘Get the cameras! We have to shoot this tomorrow.’”

The rest is history, and fitting that, given Tony Stark couldn’t help himself with the incessant witticisms through his entire tenure in the MCU, that he should go out on top.

It also emerged from the Q&A that the location for the very final reshot scene, Raleigh Studios in Hollywood, was the same place that Downey Jr did his screen test for Jan Favreau’s original 2008 movie too.