While Du You and the two sisters were leveling up, Du You naturally didn't prefer one over the other. His pet, Bubble, also gained many Law Crystals of the Light Attribute, resulting in a significant improvement.
In fact, since Bubble was inherently a 9-star creature, its improvement was much faster than the two sisters'.
Bubble didn't have any particular skills that needed enhancement, so it progressed systematically from the start. While the two sisters advanced five skills, Bubble completed the advancement of six skills, second only to Du You's improvement.
Of course, Du You's situation was special—no one could compare to him.
Additionally, Du You's Summoned Beast leveled up independently without wasting Du You's own time, which was another advantage.
