Why do you think Huck decides to keep the truth to himself (that he had figured out that the “duke” and “king” were frauds)? Why won’t he tell Jim? (CH 17-19)

The pretense most easily avoids any conflict on the raft. If the men knew that Huck suspected them, they might very well turn in Huck and Jim. Huck, after all, has stolen a slave and is trying to spirit him to freedom. Also, Huck is young and does not have the freedom to move about the way the Duke and the Dauphin do. They may be con men, but they are free con men. Telling Jim just gives Jim information that could be used against him. Such problems need not be added to the troubles they \have already built up.