This is another character, part of the Molten People living underground. He is Prince Mudslide, son of King Mudsok.
UPDATE: Added some digital color tones.
Updated digitally colored version, using Photoshop.
Mudslide is very lovable, gentle and simple minded soul. He's amazed at the upper world and desperately wants to learn . . . but like most Molten People, it takes him a very long time to learn new things. He is the only child of King Mudsok. The king loves his son dearly, but worries for his people that Mudslide will not be ready to take his place when the time comes.
A scan of the original pencil sketch, colored and shaded using Cool Gray Copic markers.