Avengers: Endgame - The Devastating Truth Of Why Cap Will Die To Save Tony Stark

2. The MCU Character Arc Formula

Ultimately, every major character arc in the MCU follows a fairly conventional story approach of origin, conflict, resolution. That's just how three act story-telling models work and you can see the way all of the original heroes are headed in those terms.

Even more fundamentally, all of the characters can be boiled down to a single statement that their arcs in the MCU have sought to contradict. For Thor, it was "I am not worthy;" for Captain America it is "we don't trade lives;" for Black Widow it was "I am a monster;" for Bruce Banner: "I am defined by conflict"... And so on. In every case, their arcs will end with an answer that disproves that statement.

The other important one there is the idea of Captain America as a constant moral heart. He is essentially invincible as a mark of him being forever committed to what is right. As long as he is able to draw breath, he will protect that, even to his own detriment. After all, he has nothing real to lose because he's already lost it all.

But both of those assumptions about Cap will ultimately be challenged in Endgame. First because his life will end and secondly because he'll lay it down for someone else. He will trade his life to give someone else a chance at the life he could never have himself. And that's exactly why Tony Stark will have no choice but to accept his sacrifice.

That's the why of the situation, now let's discuss the HOW...