The Hold Out

 is a side quest in the Fallout 4 add-on Far Harbor.

Synopsis
While Mitch won't admit it, he's worried about his Uncle, Ken, who is the last normal human still living on the Island. Living at the old Visitors Center, the bartender grudgingly admits that he wants the Survivor to check up on him...

Walkthrough

 * 1) Head to Mitch and talk to him about the quest. Debby will eventually cause him to come forward with what he wants you to do.
 * 2) Optional: A hard persuasion check will cause him to cough up 2 RadAway and  3 Stimpaks.
 * 3) Head to the Visitors Center and talk to Uncle Ken.
 * 4) Uncle Ken will chastise you for coming in and attracting more of the Island's nasty inhabitants. Upon talking to him, trappers will spawn and start attacking.
 * 5) This unlocks the Visitors center as a workshop settlement. Repulse the attack and talk to Uncle Ken.
 * 6) With a hard persuasion check after a moderate one, you can convince Ken to come to Far Harbor. Otherwise, he will stay behind.
 * 7) Return to Mitch for a reward.