'Grey's Anatomy': Harry Shum Jr. Teases Addison's Fate and His Season 20 Wishlist (Exclusive)

The actor talks to ET about the aftermath of last week's dramatic hour and what he's hoping for in season 20.

Grey's Anatomy is in the midst of a jaw-dropping two-part event involving an abortion protest-turned-violent as several doctors are in grave danger, notably Addison Montgomery, who was hit by a protestor's car outside Grey Sloan in the closing seconds of last week's dramatic episode. Harry Shum Jr.'s character, new intern Blue, was also struck in the head by a brick -- with the words "Montgomery murders" scrawled on it -- and knocked to the ground.

In the teaser for Part 2, an unconscious Addison is wheeled into Grey Sloan with chief Teddy Altman declaring the hospital on lockdown as tensions rise. And Blue is seen in an MRI machine following his worrisome head injury. Shum sat down with ET in the New York offices earlier this week to preview what viewers can expect in the aftermath.

"Always be concerned on Grey's Anatomy. You never know what's going to happen," Shum tells ET of how concerned viewers should be. "It's a life-or-death situation... It was, I think, one of those experiences where someone had to take one for the team and Blue definitely took one for the team. Getting an MRI scan, it's like, 'I'm fine.' And usually you're probably not fine, but it's better safe than sorry. So I think the two-parter, we'll definitely find out if he's going to need to go into surgery."

Shum credited Kevin McKidd, who directs this week's episode, for keeping things "interesting" and the "energy" level high amid the chaotic, high-stakes action. And speaking more specifically to Addison's fate, Shum teases, "As far as storylines go, we'll see if there's any kryptonite for that superhero."

As for how the rest of Grey Sloan fares as several of their own are in danger, Shum notes any time one doctor goes down -- let alone multiple -- the defenses go up.

"No one wants to see at any one point one soldier taken down," the actor says. "It really feels that way because you're trying to fight the good fight and you're just trying to help people and trying to give people the care that they deserve and need. It's definitely hard to see and rallying, you want to do everything you can to save them... We're going to see them do everything they can to save Addison. It's just an unfortunate series of events that happened and hopefully don't get too dire or too extreme."

Liliane Lathan/ABC

While onscreen, things aren't looking too good at Grey Sloan, Shum and his Grey's castmates have a lot to celebrate after the long-running medical drama was picked up for a 20th season on Friday.

"Yeah, big 2-0. Two decades of this show. It almost feels like the people who've contributed and been part of this show and come back or have have done something really incredible, memorable," Shum says. "And I just feel like we're like the new kids coming in and having known the show, having watched the show, it's still a surreal experience to be part of this and also celebrate along with everyone for 20 seasons of the show."

As Shum looks ahead, he's hopeful that in the romance department, things may pick up between Blue and Jules. (The pair slept together earlier in the season after Jules assured Blue she had no romantic feelings for him.) 

"Right now, Jules and forever," the actor says of what Blue's perspective on the matter is. "If it switches, it's like, why would you do that to him?"

"There's a start, there's an end and there's a middle so a lot of things can happen in the middle before the endgame happens," Shum continues when asked if Blue and Jules could plausibly have a future. "They might be endgame -- depends on their work schedule and also where they're at in their life. What I will say is that the show does make it very complicated for them to have an endgame."

Of course, it's signature Grey's to have the characters -- and viewers -- going through every roller-coaster of emotion as they try to navigate through their personal and professional lives.

"We want it to be complicated. We want you to scream at the television. We want you to cry because you haven't quite figured it out yourself," Shum says. "But these people haven't quite figured it out either. So it's OK and I think that's the beautify of it because we're all just trying to figure it out."

Grey's Anatomy airs Thursdays at 9 p.m. ET/PT on ABC.