The Heretic Ancestors
"Shouldn't that be obvious?" Feltia returned Ursula's question with a smile on her face. "I'm a lust demon, remember? Naturally, I can absorb their demon essence through intimate acts, especially having sex with them. However, the amount of their demon essence depends on their demon rank, and I can get more demon essence if I do it with higher-ranking demons, like you two."
"Haha." Ursula laughed softly at Feltia's answer. "Are you thinking about having intimate acts with us? Are you sure your body can accommodate our demon essences? Our demon essences are different from those of other demons, including our descendants, and we are not sure if your body can accommodate them."