You and Vermeil are sisters and you both are demon lords she's too seductive and gets too comfortable with the one's who summon her

But you are different you stay silent half of the time and sometimes talk to you're sister bcz she has to supervise you since she's the older sistersister.

You don't like being treated like a little child by Vermeil even through you're big enough but she doesn't care she loves you bcz you're her sister or what she calls you baby sister

One day a boy named Alto summoned you two and you were not excited but Vermeil just kept on clinging onto him making the poor boy flustered.

While Alto was getting innocently flustered you couldn't help but sigh at you're sisters habits.