On September 22, 1994, when audiences first pushed through the doors at County General, ER was unlike anything TV viewers had ever seen. It was faster, bloodier and more realistic; scenes burst with jargon-heavy dialogue; and every frame was crammed with doctors, nurses, patients and some family member who “can’t be in here.”

When the original cast was on the cover of Entertainment Weekly, that issue’s stories referenced creator Michael Crichton’s “busy fax machine” and Julianna Margulies’s Rollerblading. ER has changed a lot since then, though not generally for the better. Early seasons played up characters’ anguish: I’m reluctant to grow up, but I want to take care of people. I’m in love with the wrong guy. I’m so focused on pleasing other people that I have no idea who I am (i.e., the internal monologues of characters Doug Ross, Carol Hathaway and John Carter, respectively). And when a spectacularly terrible fate befell a character, it prompted substantive change: After Mark Greene’s (Anthony Edwards) beating, the nerdy guy-next-door became depressed, short-tempered and unpredictable; after Carter was stabbed, he devolved into drug addiction.

Over time, though, the series shifted from character-driven development toward external, and extraneous, characters-of-the-week. For a few seasons, ER became synonymous with guest stars putting in wrenching if ultimately irrelevant performances: Ed Asner, Don Cheadle, Kristen Johnston, John Leguizamo, Ray Liotta, Bob Newhart, Cynthia Nixon, Stanley Tucci, Forest Whitaker and James Woods all served short sentences at County General. Liotta died for an hour, Nixon narrated the sensations of a stroke, Cheadle had Parkinson’s and Woods had ALS—because if there’s anything more fun than watching degenerative illness, it’s watching it again and again.

Struggling to find new and interesting ways to tell stories about its ever-changing lineup of doctors and nurses, ER became a terrible catalog of the awful shit that can happen to people. Cancer, death of a husband, death of a wife, traumatic custody hearings, deadbeat baby daddies, a family member’s debilitating mental illness and stillbirth—ER laboriously milked all of these for years.

Characters who suffer for suffering’s sake form a morbid collage of disappointment, so ER tried other tricks, too. Episodes set in Darfur and Iraq? No, too newsy. Lots of slutting around? Eh, that’s not really what this show’s about. Stories that boil down to Doctors Aren’t Magic, But You Love Them Anyway? Ah, that one fits just right.

If Doug and Carol’s chaotic romance once anchored the ragtag ER family, then Abby and Luka’s relationship has picked up that torch. The party-in-his-pants new guy, Tony Gates (recent addition John Stamos), has revived the staff-heartthrob position, dormant for years, while up-and-comer Neela Rasgotra (Parminder Nagra) has taken on the role Carter once filled of the most empathetic character, our emotional bridge to the rest of the show. And the rivalry between attendings Pratt (an underrated Mekhi Phifer) and Morris (Scott Grimes) adds depth to their mutual story lines.

ER’s come close to cancellation a few times. Yet part of what’s keeping its vitals steady right now, strangely, is the phenomenal popularity of Grey’s Anatomy, a schmaltzy but obvious heir to the doctor-show throne. Ratings for NBC’s veteran Thursday show surged after rival-network ABC’s Grey’s moved to that night two seasons ago. But Grey’s reminds us of what ER does better than other shows: It makes us care. We care about serialized relationship dramas (Abby, tell him you cheated!). We care about self-contained medical cases (fruity breath! it’s diabetes!). And whether it’s the crashing patient who needs one more shock with the paddles or the crashing series that needs one more season to right itself, we care about bringing things back to life.

Jumpstart your relationship with ER Thursday 10, 9pm on NBC.