I think Black Zetsu is actually the will of the Shinju rather than Kaguya herself, and is the one who convinced Kaguya to eat the fruit in the first place like the serpent in Genesis which is a story in the Bible that inspired Kaguya's plot.
Cosuming the fruit in such a way allows the Shinju to brainwash you and make you a vessel for it to expand its influence. Unlike Kaguya, Momoshiki was aware of this and thus consumes the fruits in pill form to avoid having his personality taken from him.
Cosuming the fruit in such a way allows the Shinju to brainwash you and make you a vessel for it to expand its influence. Unlike Kaguya, Momoshiki was aware of this and thus consumes the fruits in pill form to avoid having his personality taken from him.
