I read this paragraph repeatedly before the pull to comment was irresistible. Writing the same MC for the past 8 or so years, I'm not sure sequels are actually easier. Having to maintain consistency, with previous events and character personalities, can be taxing. That MC, and the large cast I've surrounded him with allow me to explore plenty of story lines, though.
While the MC's, introduced at 15, is a political beast, his friends have allowed me to write about a music competition, American football players, fine art, an Air Force Cadet, and a few other disparate subjects. My guy's now 25 and the way I write his actions and dialogue are not the same as in the first installment. Partially due to me learning some things about writing but also because a government official does not look at life the way a teenager does.
It's definitely comfortable to write the same characters repeatedly, but it could get boring if the sequels are simply more of the same. My last multi-chapter story included a travelogue of Mexico, a Russian spy, and the MC killing someone with a gun. Based on reader reactions, I'll keep the train running for a while.
Nice interview, James.