The Flash season 4: Ranking its 10 best moments so far

9. Killer Frost saves Iris and Felicity

Season 3 of The Flash took great care in highlighting that Caitlin Snow and Killer Frost were not the same person. While not necessarily two different people, they were definitely two opposing entities trapped in one body. While the good within Caitlin managed to subdue the Ice Queen within, the season 3 finale wasn’t the last we saw of Killer Frost. And it didn’t take long before season 4 reintroduced us to her.

Caitlin initially kept her secret under wraps, but was forced to let Killer Frost out when Amunet Black began hunting her and her friends. And although she didn’t want to kill them anymore, Killer Frost still didn’t see Caitlin’s friends as her own. However, that all changed when Iris and Arrow‘s Felicity found themselves in deep trouble. Before Amunet Black could kill them, Caitlin turned up to save them. Threatened once more, she unleashed a puff of ice breath, and Killer Frost made her way through the frosty smoke to protect Caitlin’s friends — and defeat Amunet.

While Barry Allen was off enjoying his bachelor party, it was the girls who saved Central City. But the real hero here was Killer Frost. And this was the beginning of a new chapter for her, as she went on to aid the team throughout the rest of the season. She may not be Caitlin, but the two are more intertwined than ever, and it’s nice to see Killer Frost as a member of Team Flash.