Here is the full list of all 34 Demonheart achievements.
Max out both Evil and Tactful points.
Max out both Good and Defiant points.
Max out both Evil and Defiant points.
Read the book about demonspawn in Chapter 1.
Kill Mark.
Kiss Sir Brash.
Finish Chapter 3.
Decipher the message in Chapter 4.
Read all the entries of Rivera's journal.
Finish Chapter 4.
Finish the game as Good Bright and as Evil Bright.
Finish Chapter 5.
Decipher the whole message in Chapter 5.
Kiss Ari.
Ask the demonspawn as many questions as you can.
Decipher all the messages in Chapter 3.
Finish Chapter 2.
Decipher the message in Chapter 2.
Max out both Good and Tactful points.
Finish Chapter 1.
Decipher all the messages in Chapter 1.
Examine Mr. Edgardo after the dinner with Orchid.
Molest the demonspawn.