One is a tall, purple number 1 that has entirely purple bones and pitch black flesh and blood under his skin. He is kind to other algebraliens, but to every other species he has no compassion or friendliness towards them. His hands can morph freely into anything that exists. One is deeply romantically interested in Seven due to a shared interest of making objects suffer. Seven does not like him back at all, although One refuses to acknowledge this. He also knows Six, Eight, and Nine.