It would be perfect for When it Rains to be a character episode. Peridot has only just moved in with Steven, so naturally the next episode should focus on her as a character. The Crystal Gems are out of the picture for most of this episode, if the commercial and preview are to be believed, so it looks like a nice episode focused on Peridot and Steven is what we’re getting.
Of course Peridot’s ominous “it’s happening!” makes it sound like we’ll be getting a healthy dose of exposition along with our character episode. It’s still a bit early to unleash the Cluster though, so we’re expecting a few more episodes building it up before it’s finally released.