When Mekhi Phifer first joined the cast of ER, TV’s longest-running medical drama, which enters its fifteenth and final season this year, it seemed like Dr. Greg Pratt had been handed a Xerox copy of ER’s requisite character flaws: the insouciant God complex, the unstable home life, the fraught relationships with female co-workers, etc. But ER fans have seen Pratt evolve from a cocky intern into a mature confidant — which made (spoiler alert!) Pratt’s violent death on last night’s season premiere all the more shocking. Phifer sat down with Vulture to discuss his favorite ER guest stars, Pratt’’s “asshole” phase, and why killing off his character made sense.

So, Pratt’s dead. Did that come as a total shock? Or have you known since season eight that you’d be offed by a booby-trapped ambulance?
I definitely knew in advance. It’s not like I’m flipping through the script one day and I’m like, “What the hell — Pratt dies!?” We decided this was the way I should go.

You decided to have your own character killed off?
I had a great run on the show. But by the time I even got on the show, all the accolades were gone. ER had already won all the Emmys, been the most Emmy-nominated show, all the Golden Globes, so by the time I got there, even though the show hadn’t lost any of its quality, it just wasn’t getting recognized anymore. It’s one of the best jobs I’ve ever had. But it’s time to move on and do something fresh.

We hear that this season is going to have a lot of cast members returning, even the deceased Dr. Green. Any chance we haven’t seen the last of Pratt?
I don’t know! Doubtful. But I can’t say for sure, of course.

ER is famous for high-profile cameos. Who’s been your favorite guest star?
What’s the guy’s name who’s the dad on Frasier?* He was great. I love working with Sally Field, and Steve Buscemi is one of the most giving, talented actors I’ve ever worked with. And I love Danny Glover, who plays my dad on the show. He’s a very poised gentleman. If anybody grew up to be like Danny, you’d have to be proud of them.

Your character initially hewed to a lot of stereotypes — broken family, brother involved with gang violence, etc. What influence did you have in moving the character forward?
We’re like family on the set, so I sat down with [ER producer] John Wells and we always discussed the character’s next step, his next obstacle. There’s a very open-door policy with the writers on the show. I definitely knew this character was going to grow out of the asshole stage.

But you’d come so far from the young asshole — you’d accepted your brother’s homosexuality and you were shopping for engagement rings for your girlfriend on the season finale. Is it frustrating that you get blown up by an ambulance just as you become a mature character?
Not at all! I orchestrated it. It’s a great season ender — you don’t know who’s in the ambulance. It’s a great season beginner. If there was a way to leave, I’d rather go out with a memorable bang. That’s way better than Pratt being like, “Okay guys, I’m taking a job at Northwestern!”

A lot of characters are written in and out of the show — you could have just been that cocky intern on season eight. What’s your secret to ER longevity?
They enjoyed me. We became like a family, so they kept me around.

*John Mahoney

Mekhi Phifer on the Tragic Realities of ‘ER’