When this occurred, Peridot was in an escape pod that landed somewhere just outside Beach City and fleeing for her life to try and get into contact with Yellow Diamond. What she knows of this moment has just been talked about in vague terms. She's never ... watched it.

If she had a stomach, it would be churning. She lacks the figurative language to really define what it's like to see Lapis's wrist grabbed again and again by Jasper's grasping fist. Every time Jasper turns to the Crystal Gems (Peridot among them where she never was before, blending in with them seamlessly) and leers at them before the fusion takes proper shape, it fills her with such a strange sense of disgust. And it grows stronger the more she watches, uncertain of what to do, until finally, in a blind panic, she breaks and rushes out onto the beach just before Lapis extends her hand.

And before Jasper can take it, Peridot grabs it instead, shaking a bit because if this is real then she's just put her back to Jasper and she is going to get pulverized into the sand, but she can't just stand back and watch. She has to do something, and this is what she does. No turning back down. "Lapis, stop."