At least Feferi does stop when she hears Sollux's voice, and she sits up, turning to look at him approaching like a startled antlerbeast. At this point, if Dave were actually dangerous, she'd probably be dead, so it's a good thing he isn't. All her attention is focused on Sollux: the pants, the pail, the blood. Feferi's not sure which one she finds stranger but she doesn't really care. She's kneeling on the floor with blood on her lips, still wearing the strange, feathered thing she wound up in earlier. Her skates are still hanging around her neck, and it's probably better she didn't think to use them.

She shakes off the surprise just long enough to point an accusatory finger at Dave. "But he was going to come hurt you, so I was trying to stop him!"

If she was going to have to kill someone eventually, it might as well be whoever threatens Sollux or herself, right? That was a reasonable situation in which you might kill someone-- it would have been true even if they were still on Alternia.