Bruce Banner (Mark Ruffalo) and the angry "Other Guy" make peace in an Avengers: Infinity War deleted scene that ends with Hulk bursting free from the Hulkbuster armor amid a battle with Cull Obsidian (Terry Notary). The unfinished scene included in the Marvel Studios Infinity Saga box set realizes a moment first revealed in leaked merchandise, namely a "Hulk Out Hulkbuster" toy that featured Hulk bursting out of the specialized, heavy-duty armor developed by Banner and Tony Stark (Robert Downey Jr.) to thwart the green goliath's rage-fueled rampages.
The scene shows Banner plead with his green-skinned alter ego — who refused to show after a beating from Thanos (Josh Brolin) — to reveal himself before Banner is beaten to death by Cull. Seconds before Banner succumbs, he realizes they've "worked it out," and a harmonious version of Hulk possessing Banner's brains and Hulk's brawn rips free from the Hulkbuster armor. This newly-born version of Hulk then uses a Hulkbuster boot to launch Cull upwards into the energy dome shielding Wakanda, killing him.
"There was a time when Banner became Smart Hulk in [Infinity War]. It was a lot of fun, but it came at the wrong moment. It was an up, right when everyone else was down," Infinity War and Avengers: Endgame co-writer Christopher Markus previously told The New York Times. Added co-writer Stephen McFeely, "His arc was designed like, I'm not getting along with the Hulk, the Hulk won't come out. And then they compromise and become Smart Hulk."
The scene was cut and Hulk never emerges in Wakanda despite an early Infinity War trailer showing Hulk racing into action alongside heroes like Captain America (Chris Evans), Black Panther (Chadwick Boseman), and Black Widow (Scarlett Johansson).
At San Diego Comic-Con in July, Markus and McFeely admitted the above Infinity War scene "didn't work." Markus said the scene was "tone deaf" because Smart Hulk's victory came minutes before Thor (Chris Hemsworth) failed to prevent Thanos from wiping out half of all life in the universe.
Smart Hulk was instead reserved for Endgame, where Banner reveals he achieved unity with the Hulk after an 18-month stint in a gamma lab some time during a five-year time jump.
"Imagine the first act of Endgame, he's Smart Hulk in all of those scenes — meaning when he goes to kill Thanos, when they're sitting around the compound when Tony's returned — so that required some adjusting," McFeely said at Comic-Con. "And it also meant that we could use the five years as the transition, hint that he's got problems coalescing, and in the five years he figures it out. You have a couple of lines about gamma radiation and he's eating pancakes, and off you go."
Added Markus, "Also, it's like, you get it. Part of the thing we learn every time you write a movie — and particularly a movie where it's a continuing storyline — you don't have to explain as much as you think you have to. You can go to Queens, people know who Spider-Man is. I don't need to see him get bitten by the spider again. Like, 'okay, he's a combination of Hulk and Banner, I get it.' Just give me a crumb as to how it happened."