With a little thought, it is easy to figure out WHY Ryu and party would reject Myria's offer. Teepo and her believe that the Brood's power could only be used for evil. However, Ryu is never shown to commit any sort of evil. Think about it. There were a dozen instances where he could easily have become a conqueror. He killed Balio and Sunder, he is capable of intimidating anyone who comes near him by going into dragon form, Rei could easily have killed Mikba and taken over his criminal empire, Rei could easily have murdered or enslaved the McNeil residents, the party could easily have killed or imprisoned the king and queen of Wyndia and taken over the kingdom, the party could easily have ruined Rapala's economy by seizing control of the lighthouse, Momo could easily have taken control of the Middle Seas with the Black Ship effectively controlling half the continents economies, Momo could easily have taken the robot army under her control from the towns across the sea, the teleporters would make many areas opened up to sudden hit and run raids, Ryu's power could destroy any army, the entire party is able to kill Myria, a practical god, and the Brood could have easily taken over the world if they had been so inclined. Let's face it, within a decade, Ryu could have been the emperor of the entire world with little difficulty and could convert many people to his side with fear tactics. He logically KNOWS he could have done this at any time and yet, time and time again, he's used his power to try to help people and protect his friends. Myria's whole argument that Ryu's could ONLY be used for evil completely fell apart, debatably, after the events of the entire second half of the game. The fact that Ryu exists and is a good guy is proof enough that Myria is wrong.