I started on “ER” on season eight, pretty deep in the run. But, of course, it turned out that we were only about halfway done.

When I became showrunner in season 12, there were definitely places where I felt we could get back to things that we used to do well; things we had gotten away from. There was a long period in the show when the heroism of the characters was too overwhelmed by the darkness of their personal lives. We needed more of a balance.

And balance is the key, giving equal weight to what makes the fans loyal versus what keeps the show vital. Fortunately, we weren’t at risk for cancellation, so we could try things and, if they didn’t work, we could pull back. And we were lucky to have a show that had a malleable premise where you could mix genres.

You’re never going to keep everyone happy. One of the bolder moves I made came in season 14, where we took Maura Tierney’s character, Abby, to a pretty dark place. There was alcoholism and infidelity. We didn’t pull any punches, and, for a lot of fans, it was too grim. But Maura delivered some revelatory moments, and I think in the end, even the people we may have lost came back. They saw we weren’t just resting on our laurels.

“ER” showrunner David Zabel, as told to Glenn Whipp