What is Injun Joe's Impact on Tom Sawyer and Huckleberry Finn's lives in Chapter 9-10?

Injun Joe is an angry, vengeful, amoral man who thinks nothing of robbing Hoss Williams's grave, killing Dr. Robinson, stealing gold, or threatening old widows and young boys. Injun Joe's name, which is an abbreviated slang pronunciation of "Indian Joe," shows that his identity is so closely tied to his being a Native American that the townspeople - and the narrator - cannot think of him except in terms of his being an Indian. When Injun Joe, Muff Potter, and Dr. Robinson are in the cemetery to rob Hoss Williams's grave, Injun Joe begins to argue with Robinson about money. He points out that years before, Robinson had treated him poorly when he was in need, and he tells Robinson, "I swore I'd get even with you if it took a hundred years…. Did you think I'd forget? The Injun blood ain't in me for nothing." For Tom and Huck, Injun Joe represents a dark force.... evil.... danger. They are terrified of Injun Joe, and yet, Tom later places himself in even more danger when he testifies on Muff Potter's behalf.