It's a perfectly good threat. It's the sort John has used on people— it's something John has done to people, when he wasn't calling himself John. He can clearly picture what Arthur's skin would look like if it were peeled away.

So he glares balefully back, silent, still streaming ichorous tears. And grits, "I understand."

Arthur gave him so much shit, their final day together, about giving orders. John's not giving fucking orders. No one here knows the goddamn meaning of giving orders. But he— he was hasty, yes. Reckless.

Cruel. And it didn't even solve his problem.

"It won't happen again." He levels one last parting look at Levi, shoulders bowed, tendrils still seething at his feet. "I'm going back to the Convoy." And unless anyone puts a gun back in his face, he pulls himself forward through the rain like an octopus across the sea floor, and slinks away.