Candice Patton's character has been gone since the conclusion of The Flash season 8, episode 14, when Iris' illness caused her to vanish once more.
Iris has gone absent previously, but this is the longest time she's gone AWOL, which will be addressed in the next episodes of The Flash season 8.
Barry Allen worked primarily on training the show's new speedster, Meena Dhawan, best known to DC fans as Fast Track, in season 8, episode 18, "The Man in the Yellow Tie."
While Matt Letscher's Reverse-Flash was featured in the episode, Eobard Thawne's homecoming had a twist.