About the revenger, and meeting old crewmates

[jc1220]

Is the revenger an enemy; how do I encounter him/her?
I saw one of my other crewmates in town, a deserter, I had the option to kill her and forgiving her so I forgave her instead, is there any benefit to killing old crewmates?

[Iniour]

The revenger can appear after a sailor is marooned. If he survives, he has a chance to become the revenger . After that, you will have a chance to meet him in a city, and then this event will unlock another one, until a battle.
It's not an easy sequence of events to unlock, I admit.
If you decide to kill a former sailor, it's up to you to see what happens! ^^