Look like rubber bands to me. (They seem to have body, not lay completely flat like tattoos) Maybe this version of Spike has some bad habits or unwanted thoughts so he's using rubberband snapping as a coping mechanism to disrupt destructive ideation or behaviour. It would go with the sort of darker personalities theme of the story. Dunno if that is what is intended, just what seeing them reminded me of.
Look like rubber bands to me. (They seem to have body, not lay completely flat like tattoos) Maybe t
