Here is the full list of all 27 Demonheart: Hunters achievements.
Side with humanity.
Side with Thayn.
Reach Thayn's Inferno.
Sell someone's skull.
Release the trapped demonspawn.
Find Mr. Edgardo.
Reach Raze's Inferno.
Kiss Sinallion.
Board a ship.
Rescue your demonspawn ally.
Obtain Poison Attack II.
Complete all Church of Ravage quests faithfully.
Reach maximum Good alignment with Bright.
Kiss Brash.
Rescue Brash.
Obtain Poison Attack skill.
Reach maximum Tactful alignment with Bright.
Choose the young demonspawn as your ally.
Sabotage a quest for the Church of Ravage.
Sell 30 Healing Salves.
Kiss Ari.
Kiss the demonspawn.
Sleep with Thayn.
Obtain Poison Attack III.
Choose the adult demonspawn as your ally.
Reach maximum Evil alignment with Bright.
Reach maximum Defiant alignment with Bright.