'The Flash' season 3 spoilers, plot news: Dr. Alchemy is in! Candice Patton dishes on Barry and Iris' relationship

When "The Flash" season 3 premieres in October, fans can expect a better understanding of the Flashpoint storyline in light of what Barry Allen did in the season 2 finale, going back in time to save his mother. His messing with the timeline will have various repercussions, which will be the upcoming season's arc.

The most recent trailer for the series suggests that Barry (Grant Gustin) will be living in some sort of fantasy world that he created when he saved his mother. Moreover, director Kevin Smith teased that some episodes of the upcoming installment will be action-packed.

Smith, who directed season 2's "The Runaway Dinosaur" episode, will be at the helm of episode 7, which is titled "Killer Frost." The director teased that big bad Dr. Alchemy will be the highlight of episode 7.

Fans will recall that mystery shrouds the existence of Dr. Alchemy. No one knows who he is, so fans are theorizing that he might be someone Barry knows but doesn't suspect, and they have their fingers pointed at Julian Dorn (Tom Felton).

In "The Flash" season 3, Dorn will play Barry's CSI boss who thinks Barry is hiding something. However, he, too, is harboring a dark secret, too. Felton already gave a cryptic description of his character's relationship with Barry. Hence, it remains to be seen of fan theories are right on the money.

Meanwhile, Candice Patton, who plays Iris West on the series, recently dished on her character and Barry's relationship in season 3.

At the end of season 2, Iris finally confessed her love to Barry, and according to Patton, fans will be pleased with her character in the upcoming installment. In an interview with Den of Geek, she says she will try to make the romantic relationship work.

"Yeah, I think it was a long time coming back. I think Iris has always had, you know, feelings for Barry. To some degree. Some that she couldn't really vocalize, and I think being in a relationship with Eddie made it difficult for her to kind of come to terms with the fact that she had feelings for Barry, so... you know I think it was finally the moment," she said. "It was the right time for her to finally concede to the fact that she likes Barry, loves Barry, and wants to be with him."

Patton likewise said that the fact that Iris and Barry grew up together will not affect the romance since they are not siblings. Apparently, other people perceived them as brother and sister, but they don't share any DNA. So it looks like Iris and Barry will see their relationship grow further in season 3.

"The Flash" season 3 will premiere on Oct. 4 on The CW.