That's literally her family's ancestral ability.
As everyone knows, Lord Demon King also moonlights as the Demon God of Lust, one of the Seven Sins Demon God of the Abyss. Although She herself has actually mastered all the Original Sins, and could sit in any of the Seven Demon Gods' seats She fancied, in the end She still chose the Original Sin of Lust.
To this day, no one really understands why Lord Demon King made that choice. After all, while the Seven Deadly Sins are equal in theory, the Original Sin Demon Gods definitely aren't all on the same level. Anyway, in the Abyss, the Lust Faction has never been all that strong, far weaker than powerhouses like the Pride, Greed, and Gluttony Factions.
Mm, in short, the Lust Faction had always been the eternal second-to-last.
As for why not dead last? That's because the one at the bottom has always been the Sloth Faction.
