Birds of a Feather

 is a quest in Fallout: New Vegas.

Quick walkthrough
This quest can be activated after completing several jobs for the Van Graffs in Freeside. To start it talk to Gloria inside being the counter. She will say Jean-Baptiste has a job for you. Speak to him and he will task you with bringing Rose of Sharon Cassidy to him.

She will be down at Mojave Outpost unless you have already gotten her as a companion via another quest. When you bring her back to him he will reveal his purpose is to kill her. From here you can choose to let him kill her, or become hostile by saying "Shoot her and you'll be sorry" If you choose this method you will have to kill all the guards inside the Silver Shop. Alternatively you can let her die and you will be paid 350 caps.

Detailed walkthrough
1. First you will have to guard the front door. A series of NPC's will come up to you, and you must remember to allow no drunks and everyone must be searched before going in. Passing a speech check results in being paid a bonus on top of the job's normal pay.

2. You will need to deliver a package to a man a bit east of New Vegas. With a high speech check you can get 200 caps from the man.

3. You will need to bring back Rose of Sharon Cassidy to the Silver Rush to be killed. If you accept, you will lose her as a companion and subsequently fail her companion quest; however you will succeed at this quest and get a large sum of caps as a reward. (If you have a companion with you at this time you will need to split with him/her to allow Cass to follow you.)

You can also choose to resist her death. This results in a fairly difficult gunfight, especially if you're low level. Numerous guards, and one will either pick up or already equip a plasma caster, which will do tremendous amounts of damage to you. If you isolate Jean-Baptiste you can focus him down first, but he has very high DT. All the guards and his sister do not have as much, so if you need to kill the guards and his sister before moving on to him. Doing this will result in you failing this quest and no EXP reward, however, you will be able to complete Cassidy's quest for that reward. Or, you could complete her quest first and then lead her here to her death and complete both.

4. If you choose to just let Jean-Baptiste kill Cass, then Gloria will ask you to help her with one more thing. The reward for helping her is 1000 caps and the Van Graff Combat armor. What you actually have to do is kill Caesar's troops in a warehouse.

Bugs
If you choose to guard the door with Simon there is a potential bug. After 4 npcs, there will be a special NPC who will chat with Simon. If you aim your weapon at him he will stop talking to Simon but permanently stand outside of the Silver Rush. If you enter the Silver Rush, you can take the next quest to deliver a package, but once you leave the outside post, Simon will attack you as a theif of the Van graff weapons and and armor. This bug is compounded by the autosave, and can permanently deny you relation with the Van Graff.