Spoilers, even unintentional ones, can have an effect on your viewing of a film. To talk about this, I’m going to have to discuss specific spoilers about The Avengers. This is your warning.

Like a very large number of other people last week, I saw The Avengers with some knowledge of the future development schedule for Marvel’s film universe. Specifically, I knew that Iron Man 3 was well underway.

Which means that for me, and anybody else with that knowledge, when Tony Stark grabs hold of a nuclear warhead and redirects it toward the invading alien mothership, I knew he wouldn’t be killed or lost forever on the other side of a wormhole. The tension was diminished.

So why did the moment still work? Because Tony Stark didn’t know he was going to survive.

Potentially sacrificing himself to save New York and stop the invasion was the culmination of Tony’s arc. The conflict between Captain America and Iron Man centered on whether or not Stark would be willing to sacrifice himself if there were no other option. Tony was always looking for the way to “cut the wire” and not have to make that choice, but when the missile was launched, no such option presented itself.

Instead of the tension of wondering if he would survive, we get the tension of whether or not the plan would work combined with seeing the completed evolution of Tony as an Avenger. While we didn’t believe that he would die, we saw that he was willing to make a heroic sacrifice.

Now, not everybody is working on The Avengers or Iron Man 3 script. If you’re writing a spec script, there’s a near zero chance that anybody will find spoilers to it on the internet. But there’s still something to take from The Avengers and the nature of spoilers and suspense.

Say you’re writing a script about World War II. We know how that ends. What we don’t know is how it ends for your characters, and how the climactic moments of their story reflect upon the journey we’ve watched them take. The life or death stakes that characters deal with in that story are there as a way of forcing them to deal with their personal conflicts.

In most romantic comedies, the couple gets together in the end. The tension lies in watching how they get to that point. The Avengers is the same way. We have little doubt that the team will repel the alien threat and go on to their respective sequels. The core question is how will they learn to work together to achieve this?

Success or failure is just the box score. How characters come to succeed or fail is what holds our attention.