Why does Thomas allow Red Dillion to control him?
In Hal Borland's When Legends Die, Thomas needs Red Dillion in order to get started in the rodeo business. Red enlists Meo and together they teach Thomas how to ride horses in rodeo competitions. Red acts as his manager; Meo as his trainer. Red teaches Thomas how to make money from his riding which involves losing purposely on occasion so that Red can bet against him when the odds are favorable that Thomas will win. Red's scheming is only slightly profitable, but it is definitely unethical, and Thomas struggles with his pride and his morality in going along with Red's ways.
Several factors enter into the break between the two of them. The first is a rodeo in which Red bet a good sum of money on Thomas, and Thomas loses. Red is bitterly disappointed. The second is Thomas's decision that he is going to ride broncos "clean," or fairly. After being with Red for several years, Thomas has essentially outgrown him. Thomas is old enough and experienced enough now to handle himself, and he knows he wants to compete his way--no more intentional losses.