When you've completed those first few steps, you can finally go back to Lisa and choose the dialogue options below.
If you choose the wrong one, or if she doesn't mention the curse, exit to the main menu before leaving the floor and make sure you've completed every step.
- Do you need any help?
- I'll keep him out of trouble.
- He told me a dark secret.
If the achievement doesn't unlock right away, head back down to Larry and say 'So, about your curse...'