Birds of a Feather

 is a quest in Fallout: New Vegas.

Quick walkthrough
Find Rose of Sharon Cassidy, and get her to join your party.

Detailed walkthrough
Rose of Sharon can be found in the barracks of the Mojave Outpost sitting at the bar. She needs her caravan papers to clear before she'll join you.

You can get her papers cleared by performing the jobs for the Crimson Caravan. The Crimson Caravan has made an offer to purchase the caravan franchise from Cass. If you successfully complete this mission, Cass (Rose of Sharon) will be free to leave. She can join you so long as you do not currently have another humanoid follower.