Just past the burning ship in Cyseal Docks you will find three sailors in search of new jobs.
"Captain Jack" and "The World Needs Guts" are the mutually exclusive trophies related to these sailors so make sure to reload a save to get both trophies.
The Fabulous Five recruiter is right outside the King Crab Tavern. Agree to join the fabulous five then convince him to take on the sailors then inform them for the other trophy.
Reload to get the sister trophy. Captain Jack is in the center of Cyseal among the merchant stands. Speak with him and he will agree to take on the sailors. Return to them and let them know for the trophy.