It should come as no surprise that Barry Allen will (likely) escape the Speed Force when The Flash returns this fall. But when he does, he’ll return a changed man.

In the season 3 finale, Barry (Grant Gustin) sacrificed himself to protect Central City from a lightning storm by entering the Speed Force. When the show returns, Barry will have been gone for six months when what appears to be a Samuroid — a robotic samurai warrior from the comics — threatens Central City, forcing Team Flash to up its game in freeing Barry from the Speed Force. However, they may not like what they find.

“The way I see it is, time is non-linear and everything is happening at once in the Speed Force,” Gustin tells EW. “In some ways he’s had an awakening and he’s had a rebirth. Our first episode is called ‘Reborn,’ and it is a rebirth for Barry, but he’s kind of scrambled, too, because he’s experienced so much so quick over the course of six months, even though for him it was an eternity. He’s not Barry when we see him for the first time.”

Barry isn’t the only one who has changed, though. In the months since he’s been gone, Iris has taken over Team Flash, but she’s definitely struggling with Barry’s absence. “Obviously they had a wedding planned,” Patton says. “They did defeat Savitar and thought they were going to live happily ever after, but at the last minute Barry decided to go into the Speed Force, so she’s really, really going through it. She’s choosing to be as strong as she possibly can. Barry told her to keep running, keep being strong, and that’s what she’s doing. When we pick up season 4, Iris takes the mantle of Team Flash; she’s the leader, the boss, the overwatch for Team Flash while Barry is gone, which is a cool new role for her to play.”

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However, don’t expect Barry and Iris to fall back into near-marital bliss when he returns. “There’s going to be some trust issues,” Patton says. “He left and didn’t really ask her or discuss it with her. He just kind of does things and comes back and says, ‘I hope you’re okay with that.’ They’re going to have to really work on their relationship before they actually tie the knot — if and when he comes out. There’s going to be some work that needs to be done before they actually put rings on each other’s fingers.”

The Flash returns Tuesday, Oct. 10 at 8 p.m. ET on The CW. Get more scoop and watch the season 4 trailer here.