As noted by Indiewire, it appears that Iron Man 3 could have taken a radically different direction. Spoilers ahead!
Director Shane Black and writer Drew Pearce appeared on Empire Magazine’s film podcast to discuss the movie, and interestingly enough talked a bit about the plot points which got cut out prior to filming. Notably, a few villains were cut and replaced with the ones seen in the film, but also — it appears that one of the originally planned subplots for the film would have seen Gwyneth Paltrow’s Pepper Potts sleep with Guy Pearce’s Aldrich Killian partway through the movie.
Not entirely of her own will, though! It looks like this would have been as a result of Killian’s ‘Extremis’ upgrade, which would have allowed the villain to be ‘pheremonially enhanced’ that Pepper ‘couldn’t resist him’. Having slept with her, he would then have posted a sex tape to broadcast on national TV. It’s a little similar to a storyline which happens between Iron Man and Black Widow in Ultimates 3, in fact.
But! Didn’t happen. Which is good, because frankly it seems like it would’ve thoroughly disrupted the rather lovely relationship between the two leads. As well as being, y’know, absolutely creepy and weird. It was thrown out at the writing stage though, and was never planned to be in the film proper. But it could have been!
You can listen to the whole of Empire’s podcast – the interview starts 45 minutes through – on their website, right here. And I’d really recommend it actually, because the presenters are knowledgeable and canny in their review of the film, bringing up obscure Marvel references in their comparison between the comic and the film.