Looking at Keto, in the previous exchange, Mephisto had learned of the Divine Authority she wielded—a counterfeit, false 'beauty.'
At present, this power might not be useful. But once humanity can reproduce, it would indeed become a very useful tool.
The first wave of souls, with the Forethinker's foolish actions, Mephisto was quite confident now. Currently, for the perfect fulfillment of his covenant with the Lord of the Nine Hells, he had to think ahead about how to continuously obtain souls.
He couldn't be this blatant in the future, otherwise, whether it be the deities on Mount Olympus or the existences in the Spirit Realm, they likely wouldn't let him off.
"As for what I need you to do... actually, right now, I rather need the assistance of Lady Megaera."
Looking at the goddess of envy beside him, Mephisto slowly promised:
"Stir the hearts of humans with envy, my lady. Provoke their jealousy towards immortality, towards power, but do not make it too obvious."
