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. To get her to follow you, you will have had to complete the quest 'Heartache by the Number'. 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 Rush. Alternatively you can let her die and you will be paid 350 caps.

It is possible to kill Jean baptise and get away with it if you have already started this quest and want to purposfully fail it to save Cass. You will fail the quest but if you want to save Cass and NOT fight the guards you will need to use the stealthboy, sneak up and pickpocket Jean and place a grenade and let him explode you will have to back up in the nearest corner or space available to not get detected by the guards but it is fully possible to escape from there withouth fighting everyone.

Detailed walkthrough
1. First you will have to guard the front door. A series of 4 NPCs 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 on the third customer results in being paid a bonus on top of the job's normal pay. The fourth NPC will be carrying a bomb. If you choose to let him in, he will blow up the entire store (and any items inside of the store as well), failing the quest.

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 bring her to Jean-Baptise and allow her to die while in dialogue, you will lose her as a companion and fail her companion quest if you have not already completed it. 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.

Normally you are forced to either let Cassidy die or fight the Van Graffs as soon as you initiate dialogue with Jean-Baptise, but if you have the Terrifying Presence perk, you can exit the dialogue and take more time before coming to a final decision on how to handle the situation.

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
1. 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.

2. Also during the door guard section of the quest, if the Courier denies the fourth customer entry he will turn hostile. If the Courier deals the finishing blow in the resulting fight, Simon may freeze in place. He is supposed to walk over to the corpse, but will instead stay next to the door with his weapon out and become unresponsive to dialogue. He will stand there staring at the Courier, and will never speak the dialogue that triggers the fifth customer. He will, however, become hostile if you go far away from the Silver Rush, like normal. The easiest way to avoid this is to let Simon kill the fourth customer by himself - he's more than capable.

2. Jean-Baptiste's body can't be looted, nor when his body is a pile of goo. This problem occured after you refuse to gun down Cass with him (after the package quest from Gloria). This is really troublesome since he holds the key to unlock the door of the Silver Shop staff's private area's. This can be solved by pickpocketing the key from him. [PC VERSION, confirmed].

3. It may happen, that both Cass related quests fail when you refuse to shoot Cassidy and kill Van Graff's instead.

4. If the 4th customers body is not vaporised, Simon may ask you to help him move it. This can result in Simon, the Silver Rush crier and 5 Van Graff Guards becoming hostile outside, and the Van Graffs inside becoming hostile.

5. After convincing Cass to travel with you, many of the weapons on the tables may be in very high condition (example: Multiplas rifle at full condition). However, taking the multiplas rifle (or any other gun as far as I know) will cause any attempt at lock-picking, hacking a computer, or looking through a scope to become a blank computer screen obscuring your view. You can still function however, but attempting to do any of the three things will obviously be extremely difficult. The only solution found so far is to reload to your last save before you took the weapon(s) and make sure they are not in a "to good to be true" condition when and if you try and take them again.