Killer sans in this au is a skeleton who has a red ecto shark tail. He has a floating soul that is also red and looked like a target. He also has black substances running down he's face. This au every monster or creature lives in the ocean called leviathan. There, there was a huge skeleton octopus who was filled with negativity and will kill anyone he was called nightmare a black octopus. Killer works for him and he takes he's orders. Killer is more comfortable to talk to nightmare