There are similarities between the design of Oxygen and Hydrogen because it is important for the audience to believe that these two characters could combine to create the Water character. The large mouth and 'quiff' are important aspects of Oxygen's design, with the former connecting to breathing and the latter to Oxygen's kindly yet mischievous nature. The hands have not been designed yet, but I partly know how they're going to look. The grayscale is not representative of Oxygen's final colour scheme. My favourite thumbnails are 24, 14, 20 and 09.