Viewers of The Flash will be seeing more of Mark Blaine/Chillblaine (played by Jon Cor) in the show's ninth season. According to Deadline, Cor has been upped to a series regular for the final season.

Blaine was first introduced in the show's seventh season. In the Season 7, Blaine framed Killer Frost (played by Danielle Panabaker) for murder and theft. Frost later stopped Blaine and proved that he was the one who committed those crimes, and he was sent to prison. However, he was later released after he agreed to become a state witness. At the end of seventh season, he teamed up with Frost to stop an army of clones of the villain Godspeed. Mark and Frost then dated throughout the eighth season of the series. After Frost died, Mark agreed to work with Caitlin Snow to try to bring her back to life.

In a character description for Mark Blaine, it says that Frost's death inspires Mark to become a hero himself. Blaine isn't the only villain that The Flash (Grant Gustin) has gone up against to switch sides. One of the show's earliest villains was Captain Cold/Leonard Snart (played by Wentworth Miller). Snart was later recruited by time traveler Rip Hunter (Arthur Darvill) as part of a team to stop Vandal Savage (Casper Crump) in the first season of fellow Arrowverse series Legends of Tomorrow. Snart later sacrificed his life at the end of the season. Snart's partner in crime Heat Wave/Mick Rory (Dominic Purcell) also switched sides after joining Rip Hunter's team. Killer Frost herself was originally an adversary to Team Flash when Caitlin first began turning into her after the Flashpoint event in the show's third season.

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Another casting change for the ninth season of The Flash will see Jesse L. Martin, who plays Joe West, not as a series regular for the season. However, Joe will still appear as a recurring character throughout the season. The Flash ending with its ninth season was announced in August. Season 9 of The Flash will not only conclude the series, but also The CW's Arrowverse franchise, which began with Arrow in 2012. "Nine seasons! Nine years of saving Central City while taking audiences on an emotional journey full of heart humor and spectacle," said showrunner Eric Wallace when the series ending was announced. "And now Barry Allen has reached the starting gate for his last race."

The ninth and final season of The Flash will air on The CW in 2023. The show's previous eight seasons are currently available to stream on Netflix. In the meantime, check out a promo for the show's eighth season below: