He wasn't afraid, for each time he descended to the mortal realm, he would cast out all of the "Source" force that did not align with his path and pour it into Zhu Wu. When he returned to the Heavenly Palace, he was always "stripped bare," which made the eyeball trust him completely.
After all, aside from the exceedingly loyal you, who would be willing to relinquish the Source force they had obtained? Look at those five dragons; they'd cling to the Source even in their sleep and while eating.
Only you! To the eyeball, you were the epitome of loyalty, serving wholeheartedly. Naturally, it would richly reward you, showing the other five dragons the benefits of fidelity, setting an example for them.
Day after day, year after year, with the continuous infusion of the Source, Zhu Wu's strength skyrocketed.
