Here is the full list of all 18 Queen of Thieves achievements.
Romance Fredrick with Thalia
Romance Melvin with Joanne
Romance Tiberius with Kira
Finish Game in Visual Novel Mode
Romance Therjalla with Thalia
Romance Moirgane with Joanne
Romance Mary-Ann with Kira
Earn 50.000 gold
See Arianna in Sexy Outfit!
Clear The Catacombs Of Undead
Romance Therjalla with Joanne
Romance Moirgane with Kira
Romance Mary-Ann with Thalia
Romance Fredrick with Kira
Romance Tiberius with Joanne
Romance Melvin with Thalia
Defeat Raul
Defeat Raul Demon