Pepper Potts (Gwyneth Paltrow)
Character Analysis
Pepper is Tony's executive stand-in and girlfriend. She basically runs his company for him while he's off saving the universe.
Their relationship was covered pretty thoroughly in the first two Iron Man movies, and with this one already chock full of characters, director Joss Whedon originally wanted to leave her out. (Jane Foster, Thor's girlfriend, gets left on the sidelines here too.)
But Robert Downey felt that Pepper was vitally important to Tony's character and made sure she had a part in it despite the fact that Gwyneth Paltrow 1) doesn't do a lot of walk-on roles and 2) doesn't come cheap.
But why? She certainly doesn't do much besides banter with Tony and give him someone to call at the end, so on her own, she barely exists as a character at all. However, she gives Tony someone worth fighting for…and more important, she's possibly the only person Tony values more than himself (maybe the only person you can say that about).
It's not much for this film, but it does stress that she's a part of Tony's life in important way.