To unlock the Secret Lives trophy in Assassin's Creed Liberation Remastered, you will need to complete all 15 of the persona-specific side missions.
These missions are broken down into three categories that each contain five missions and you will need to be dressed in the right persona to for them to appear.
Plot: Lady Persona
Detective: Slave Persona
Contracts: Assassin Persona
All of the Plot and Contracts missions can be found in New Orleans. Three of the Detective missions can also be found in New Orleans, with the last two being located in the Bayou.
You won't need to fully synchronise them for this trophy, or any of the other trophies in the game, so they are relatively simple and short to complete.