In Iron Man 3, the Extremis virus created by Aldrich Killian gave its users tremendous powers, such as regeneration and super strength. However, having these special abilities didn’t make them invincible. Case in point, Ellen Brandt, played by Stephanie Szostak, who was sent to stop Tony Stark from investigating the death of Sergeant Chad Davis, whose body rejected Extemis and incinerated him. Tony was able to defeat her using his ingenuity and kitchen equipment, but apparently the filmmakers originally planned a different way for her to die.
In the scene’s original storyboards posted on FilmSketcher (via ComicBookMovie.com), the fight primarily takes place outside a diner in the rural Tennessee town that Tony had plugged into his armor’s flight plan. Ellen fires several shots at Tony, and when she runs out of bullets, she melts the gun and throws it at him. She misses, but the flaming ball knocks over a utility pole that drops power lines on top of her. Tony dives for cover, and the resulting explosion incinerates Ellen. In the final cut of the film, Tony and Ellen fight each other inside the diner. She has the upper hand during most of the brawl, but her demise comes from a combination of Tony turning on a gas valve and tossing a pair of dog tags into a microwave. The resulting blast knocks Ellen into some power lines, electrocuting her to death. The woman can walk through fire and withstand gun shots, but Extremis can’t handle an overload of electricity.
The storyboard artist Darren Denlinger said the scene was "trimmed to fit locations" rather than just to change the cause of her demise. We saw from Pepper Potts killing Killian that if an explosion is big and powerful enough, it can incinerate an Extremis user, but being electrocuted shows they can die the same way a normal person can. It’s also more satisfying that Ellen’s death should came as a result of Tony’s quick thinking rather than just as an accident. After all, this whole movie is about Tony being at his lowest, and it’s fun to watch defeat the bad guys without using his armor. In the original scene, she just misses him, so she’s inadvertently responsible for her own death. Tony probably doesn’t care since he’s simply trying to stay alive, but for the audience, it’s more fulfilling to watch our hero save himself.
You can check out Ellen Brandt’s full death scene above to compare which was better, but both of them have the same thing in common: power lines screwed her over.
