I found the movie script of Iron Man 1 online.
There was a part describing the character of Tony Stark as an outlandishly confident yet morally corrupt womanizer.
A renaissance man de-programmed of societal conditioning who goes after what he wants unapologetically.
It struck me that I would have never guessed that aspect in Tony's character, but RDJ had this vibe oozing from the get-go.
Stark's nature of being relentless in his overall life mission, a lot of which are non-seduction goals along with his appetite for bedding hot women in a daring, adventurous yet unbashful manner drew me to that character.