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