The Bourne Identity happened to Tony almost by accident. Director Doug Liman had rejected one of his films, and Tony got leaked a script that the director was allegedly filming. Tony hated what he read and went to see the director, merely curious about his own script's rejection.
Things more than fell into place with that one meeting, and Tony went on to write the entire Bourne series. Today, more than anything, Tony is a well-respected and prolific Hollywood script doctor, coming in to snip scripts and make them screen-worthy.
He doesn't count them as film's he's written, really, and justifiably winces when Michael Bay's Armaggeddon is mentioned. 'I don't know what number writer I was. I worked on it for a couple months,' he told Rotten Tomatoes of the silly blockbuster. 'I did exactly what I wanted to do. I got in, I did what I had to do, made some people happy, I got out. Let's just leave it at that.'
A still from The Bourne Ultimatum, 2007