MCU: 12 Changes From The Comics That Were Completely Justified

3. Tony's Arc Reactor - Iron Man

In the comics and up until the end of Iron Man 3, one of Tony Stark's defining characteristics is the fact that the arc reactor that powers his suits is sited in the middle of his chest as a means to keep shrapnel from shredding his heart.

It was an ingenius way of making his relationship with technology more organic and it meant we got to see an interesting take on the technology poisoning him in Iron Man 2. That made for some serious complexity that made an otherwise terrible film occasionally watchable.

But unlike in the comics, in Iron Man 3, Tony was somehow able to get over the fact that the shrapnel in his chest would kill him if removed and simply got a good enough surgeon to remove it. It might have seemed something of a cop out, but it represented the end of a clever, complex arc focused on Stark's morbid fears of mortality and vulnerability, and it was a good change to make.