Kill the Lone wolves and invite Corbin Day to Lady Vengeance.
You met a fletcher called Corbin Day in the encampment of the Lone Wolves. He was forced by Roost Anlon to come and work for them.
After you killed the lone wolves. Talk to Corbin and invite him to Lady Vengenge. No XP rewarded upon completion, but Corbin Day will serve as your fletcher on board the Lady Vengeance.
Tips & Tricks
Unlock the quest by talking to Corbin Day before fighting Roost and tell him he doesn't look like a lone wolf.