Prideful

Lucien knows that he cannot boost thousands of Mermaids and Nagas in time for them to reach the Mermaid Kingdom's capital before too many Mermaids die.

It makes him feel like he's failed as their future king.

But then Lust says she has a plan, and he knows she wouldn't make jokes at such a time, so he gets really excited to know what it's about.

"Come on, my love; don't keep us waiting."

The beautiful sin of pleasure only ever has one kind of plan, so that couldn't be any different now.

"You can't boost all of them in time alone, so you have to use the powers of the other sins to create a sinful aura that can reach thousands of them at once."

Lucien remembers how powerful the aura he could create with Envy and Sophia was, but they aren't there; it's actually just Greed and Pride now.

He doesn't want to say that out loud, so he uses mind communication to talk to Lust.