For you to unlock it you have to meet three conditions:
- You have had to met Cindralith the Spirit of Ashes.
- You have to drink the poison Keri warns you about.
- And you have to gain full vodyan respect.*
*(Always say "Veyla drithan" whenever it comes up, during the meeting say you're here about the Deep Ones or offer to help with Sec, and say Angima at the end of the meeting. Fluff pillows, learn the language and get the drinks [don't forget to taste the poison]).
If you do all that a scene will occur when you are talking with Kaylee on the ship. Answer "Both" during that scene.
Enjoy! ^ ^