Here is the full list of all 8 Demons Happened achievements.
A successful therapy
Probably not the most satisfying conclusion, but you got what you came for
Don't get used to it, it's terribly expensive
I feel observed
Revenge for Sandy Claws
Interviewed citizens agree he deserved it
It resonates with me
Fun fact, the game was once called Demon Haunter but the pun kept getting autocorrected