|Why is her lighning purple? Who knows.|
Most of “Run, Iris, Run” is properly Golden Age. “Give the girlfriend the hero’s powers for a day” is a classic comic trope, back when girlfriends were just girlfriends and not characters in their own right, which is, I’m sure, how the Flash creators think of Iris despite whatever evidence to the contrary exists.
Anyway, there’s a guy who can steal powers from one person and put them in another, and he does it to Random Fire Guy and then he does it to Barry and Iris, and don’t ask how the swapping mechanics work because the episode doesn’t give a fuck. Sometimes PSD touches you and takes your powers and sometimes he doesn’t.
So Iris learns that it’s tough to be a speedster and Barry learns that it’s tough to talk to a speedster from behind a console and Ralph learns to be more brave and less of a selfish dick for the fiftieth time this season. It’s all fairly inoffensive as Flash episodes go.
The B plot is Harry inventing his version of DeVoe’s Thinking Cap to find the last two bus metas. In a rare bit of sanity for this show, Harry argues that he has to do a super dangerous stupid thing because it’s the only option, and Cisco argues that he shouldn’t do anything because it’s too dangerous and stupid, and they settle on a middle ground that’s a little dangerous and a little stupid and ultimately effective. Imagine that!