Here is the full list of all 16 Demonheart: The Ice Demon achievements.
Bring Esmius some wine.
Make a mess on Eniri's desk.
Have a secret affair with Sirath.
Defile the Mistress's bedroom.
Be saved by Zhan.
Be saved by Nissa.
Be saved by Eniri.
Save yourself with dark magic.
Lie to Mother.
End up somewhere you didn't want.
Reach a happy ending with Sirath.
Reach a happy ending with Esmius.
Reach a happy ending with Nissa.
Become the mistress of the house.
Learn Nissa's real name (I).
Learn Nissa's real name (II).