"The Flash" spoilers hint of a "real family affair" as the series delves into Cisco's background, as Felicity will apparently have an intergral role in the story arc of the world's fastest man.

Matt Webb Mitovich dished spoilers for "The Flash" on TVLine as he wrote that Cisco's brother, played by Nicholas Gonzales of "Sleepy Hollow," and Captain Cold's sister (Peyton List of "The Tomorrow People") will be introduced in the show for episode 16.

Captain Cold's sister, Lisa Snart, plays the Golden Glider in the DC Comics universe. She used to be a figure skater who wanted revenge on Flash whom she accused of killing her boyfriend. She uses skates than can create their own ice.

"We're definitely going to see Cisco in his home environment, which is fun," showrunner Andrew Kreisberg said. "Some of it's based on the comic book work that Geoff Johns and Sterling Gates and I did, and some of it's our own invention."

Meanwhile, the executive producer said that Felicity won't just be a random passersby during future "Arrow" and "The Flash" crossovers.

"In episode four of 'Flash' when Felicity came by, it wasn't just a gag to have Felicity come by. It really was integrated into the story," he said per Inquisitr. "When you reach what's going on in 'The Flash' at that point in the season, Barry is really at a crossroads. Having Felicity come by exactly when he needs her really plays into the whole storyline"

Ray Palmer will also swing by, a lot, because he just loves STAR Labs being the technology nut that he is.

"We get to see Ray so happy to be in STAR Labs," Andrew Kreisberg added. "With Cisco [Carlos Valdes] and Ray, they're new best friends. The STAR Labs team is going to help Ray further his ATOM project."

Watch out for more "The Flash" spoilers as the CW series airs Tuesdays at 8 p.m.