The Flash: Grant Gustin Teases Barry and Oliver's Final Season Reunion

The Flash returns with new episodes this week, but Wednesday's episode of The CW series isn't an ordinary run for the Scarlet Speedster. The episode, "It's My Party And I'll Die If I Want To" will see not only the return of Keiynan Lonsdale as Wally West/Kid Flash, Sendhil Ramamurthy as Ramsey Rosso/Bloodwork, and David Ramsey as John Diggle, but it will also see the return of Stephen Amell as Oliver Queen/Green Arrow, the latter of which fans last saw during "Crisis On Infinite Earths" when Oliver sacrificed himself to save the Multiverse. With all the returns in the episode, the reunion between Barry and Oliver might be the one that fans are most excited about, but according to series star Grant Gustin, it's not something he ever thought was possible.

Speaking with TVLine, Gustin said that having Amell return as Oliver Queen wasn't on his "wish list" for The Flash's final season because he didn't think it was on the table — and that he really didn't know what to expect for the final season, either.

"I didn't think it was on the table, honestly," Gustin said. "So, no, I mean, I didn't know what to expect. I realized going into the season I probably hadn't spent a lot of time thinking about how it was going to end over the years because you're just going and you're going and you just think it's going to keep going and you don't think about how it's going to end. So, even as we were making the season, I didn't know what was in the final couple of episodes up until I got those scripts. I stopped asking a lot of questions a long time ago and just kind of read the scripts as I get them and let myself be surprised."

Fans will get to see how exactly The Flash was able to bring Oliver Queen back when the episode airs on Wednesday, but in addition to the reunion between The Flash and Green Arrow, the episode will also feature what Gustin said was a "big sequence" in terms of action — and Danielle Panabaker, who is directing the episode, told the outlet that it may be one of the biggest stunts ever done on the series.

"My understanding is one of the stunts we did was, I think, one of the biggest stunts that has ever been done on Flash," Panabaker said. "And we did a fight sequence that was my homage to the incredible fight sequences that they did on Arrow for all those years. So, it' a packed full episode and I'm grateful that they believed in my abilities as a director and felt comfortable giving me an episode of that scale, because it's not just the guest cast. It's huge. It was a pretty ambitious episode."

You can check out the official episode synopsis for "It's My Party And I'll Die if I Want To" below.

HAPPY BIRTHDAY, BARRY; STEPHEN AMELL, DAVID RAMSEY, KEIYNAN LONSDALE, AND SENDHIL RAMAMURTHY GUEST STAR – Team Flash throws a surprise birthday party for Barry (Grant Gustin) but things go terribly awry when Ramsey Rosso (Sendhil Ramamurthy) crashes the festivities. Danielle Panabaker directed the episode written by Sam Chalsen & Emily Palizzi.

The Flash's final season airs Wednesdays at 8/7c on The CW. "It's My Party and I'll Die If I Want To" airs April 26th.