Here is the full list of all 17 Belle-de-Nuit achievements.
End up in a relationship with Amaryllis.
End up in a relationship with Lou.
End up in a relationship with Sebastian.
End up in a love-hate relationship with Sebastian.
Find out Lou's secret.
Win your duel against Sebastian.
Secure a tie in your duel against Sebastian.
Save the Belle-de-Nuit's finances.
You've got a four-legged friend!
Fool everyone into believing in your false identity.
Tie down Sebastian with ribbons, to spice up the night.
Win at the game of La Bête, getting Amaryllis to strip completely.
Catch the bouquet for a loved one.