I'm still not quite sure on what to do with the side kick but I'm hoping that's something that will fall into place once I've got more of an outline on the story.
Native American Mythology
Indigenous North American belief systems include many sacred narratives. Such spiritual stories which are deeply based in Nature and are rich with the symbolism of seasons, weather, plants, animals, earth, water, sky & fire. The principle of an all embracing, universal and omniscient Great Spirit, a connection to the Earth, diverse creation narratives and collective memories of ancient ancestors are common.
To narrow down the search a bit I'm going to look at their stories of evil spirits.
The Wendigo is a demonic spirit believed by Algonquin-based Native American tribes to possess humans and turn them into cannibals. The "monster" version of the mythical creature is human-like, but very tall and gaunt, with deeply sunken eyes and yellowish, decaying skin. They are impossibly thin and have an unending hunger that craves only human flesh. Below are examples of a Wendigo.
Along side this I also found that a number of Native American mythologies feature paired or opposing characters or qualities. Twins or sets of brothers appear in many myths and legends. For example, in Iroquois mythology, Earth Woman gives birth to the twin brothers Good Twin and Evil Twin. Good Twin creates light, forests, and food plants, while Evil Twin creates impassable mountains, mosquitoes, and a toad that drinks all the water. After a long struggle, Good Twin finally kills Evil Twin. However, Evil Twin's soul and his creations survive to make life difficult for the people that Good Twin brings into being.