In the Cave Mansion of the Golden Peng Clan's Demon Ancestor, Lin Yi constantly sought advice about various subjects, asking the Tribulation Demon Patriarch to explain things for him. The questions he posed were carefully prepared, and tremendously helpful in enhancing his own cultivation and his overall strength.
These "sheep" ripe for shearing were all old demons who had lived for over ten thousand years; to learn everything they knew would take hundreds or thousands of years, and that would only be the beginning.
Of course, in return, Lin Yi occasionally shared with these Demon Patriarchs his insights into the Five Elements and the Laws of Heaven and Earth, though they were quite basic.
Having accepted his teachings, these Demon Patriarchs established a teacher-student relationship with him, and every so often, as befits a teacher, he would receive gifts of gratitude from his demon student disciples.