Karrin was the security officer back in the bunker where relinquish's citizens came from. She was known for having an iron fist, but never used it unless she needed to. Her people skills led to her becoming the leader of the bunker, and she is the one who decided to let the bunker's residence go outside and make a town.
Relinquishing hope: Karrin needs help destroying the floaters and coyotes that threaten her town. She also needs plastic explosives to destroy the vault door to the armory. Karrin reveals her guilt to creating the town and begs the Vault Dweller to help her.
Find the Water Chip: Karrin will give you the rope after you help her town. She will also tell you she thinks there is a water chip in Vault 15