Why wasn’t Mark Ruffalo’s Hulk getting angry in Infinity War? What is the real reason behind it?

 

The Russos have explained it themselves:

“This was an interesting journey that we went on with Banner, trying to decide how to move him forward in the Marvel Universe.”

“What makes him (Mark Ruffalo’s Hulk) unique is that there’s a host body that is being fought over by two distinct personalities who hate each other, and both want control of the host body.”

“We thought an interesting direction to take him in is: Well, what if Banner, who typically uses the Hulk (Mark Ruffalo) to solve crisis situations — what if the Hulk were no longer interested in solving those problems for Banner? The relationship is becoming increasingly dysfunctional. He’s tired of playing hero to Bruce Banner.”

So there you have it. They thought it would be interesting to pit Bruce Banner and Hulk against each other for the entire movie.

And then they wanted to create this guy:

Merged/Smart Hulk aka Professor Dab.

They needed him in Endgame to help with the time machine, time heist, and do the snap.

We need to keep in mind that both Infinity War and Endgame were shot back-to-back. So the plot of Endgame was probably already in the filmmakers' mind when making Infinity War.

So they probably thought of Smart Hulk when filming Infinity War but had to decide when to merge both Bruce and Hulk. And they decided to do that in Endgame rather than Infinity War (that too off-screen).

Therefore, to accomplish this, no more Mr. “I’m always angry.”

They could have tried killing off Bruce, like in Ragnarok:

And force the Hulk to come out:

But the filmmakers had other plans. It was their story to tell and that is exactly what they told.

They explained Bruce’s and Hulk’s dynamic in Infinity War better in a deleted scene:

Gotham Rajeev's answer to How did Bruce Banner manage Hulk to give his consent to become Professor Hulk in Avengers: Endgame?

I’ve also explained what I think of Hulk’s portrayal in the MCU:

Gotham Rajeev's answer to Do you think the depiction of Hulk was fair in the Avengers franchise?

Image Sources: Google Images