It's funny, I don't know why I never got Fallout 3. Oh wait, yeah I do... SecuROM. Good thing Steam exists. Anyway, I am late to the game, but to me it is new, and I've been playing it obsessively for a week now. I've started my game over, because Lucky Harith died. Bah! I know this game uses the Oblivion engine, but I never expected it would carry over the same issues. But I have read about reverse pick-pocketing things onto people to help them survive. So this leaves a lot of questions for me. 1) Does it matter what condition the stuff is in? 2) Do NPCs ever repair their own stuff, or does it degrade to 0 health and stay that way?

What is the best way you've found, to help them stay alive? And where can I get the good stuff to give them? I've level 15 and only have 3 sets of power armor which is now 1 set after repairing them. I have only done a few quests, so I don't even know how I've leveled up so high. I've mostly been exploring the map and finding skill bobble heads. I'm working on a "perfect character" build. Going good so far. At the end of my explorations I fast travel to Megaton and wait until I see all 4 merchants still live, and so far they do. But I have stayed away from the DC area, so maybe that's why.

Those merchants are not heavily armed, or armored. So yes, you need to reverse pick-pocket (RPP) better gear on them. Whatever I can get, at whatever level I am, that I can repair fairly decently, I give to them. I usually wait until night, use a Stealthboy, SAVE MY GAME, then try repeatedly to rpp better stuff on them. They will not repair their own gear. But the gear that you DO give them, will never degrade. If you give them weapons other than their default weapons, then you must supply them with ammo. I usually hand over brand new Chinese assault rifles and loads of .556 ammo, as I don't use this ammo as much as say, 5 mm ammo.

All this said, I usually wait until I can get power armor in mint condition, before I rpp stuff on them, and hope they don't die in the levels that I do not help them. I was walking near a landmark, and saw a brahmin in the distance, but no companion. I looked around, and all the raiders were dead. And, following a bloody trail, found Harith, dead, behind some rocks. I took his key, ran like hell to the brahmin, and helped myself to what is arguably a gamebreaker in terms of gear from his brahmin, at level 4. Don't forget to arm their guards as well.

They don't actually use up the ammo you give them, I have tested this by giving them a gun with only enough ammo to fill it (24 for an assault rifle, for instance)... then punch them in the face and they shoot me about 100 times before I die. I gave Harith a laser rifle and 12 ammo and he never ran out on me, either. I tested this for about 30 minutes to see if I wasn't dreaming. My repair skill is 75 now, and I will add 10 more to it next level. I'm glad their stuff doesn't degrade because I can repair things pretty good now. The only question left is, where to get some good stuff for them. Even after all I've killed, I only have 1 mini-gun repaired as far as I can get it, 1 Chinese assault rifle repaired as far as I can, and some combat armor. I mean, I have only run into 3 enclave idiots who tried to kill me, so I don't know where to find more to get power armor for them. And I haven't seen many Chinese assault rifles or mini-guns, either. And if I wait too long, more powerful enemies will start appearing, making it even more likely they will die.

Oh, and one more question. They always have 3 stim packs on them. I wonder, do they use these at all, and if so, do they replenish themselves. The wiki says to put more on them, it's not very specific though. It also says the railway rifle is a great weapon for all of them, I wonder if that is true.

That's interesting about the ammo usage... they use it up on my 360. I have to replenish, but not every time I see them, maybe every four times. As for Chinese Assault Rifles, there are a buttload at Mama Dolce's, in Falls Church. You might want to bring a companion as well, due to the large amount of rifles there. I go here to fulfill my quest at Lock n' Load. Depending on your level, off the top of my head:

1. Enclave Patrol with Deathclaw kittycorner to Dukov's place. At higher levels you will also get a dropship.
2. Enclave Patrol with 3 Tesla Armored Enclave across the street from the Arlington Library.
3. " " with either a minigun or a gatling laser just north of Girdershade

The railway rifle is cool, the train whistle rocks. But I end up dealing more damage with other weapons, so after using it for a couple of levels, I usually retire it. I supply all companions with Buffout, as they seem to use this more than food items. I find a lot of enemies carry food items on them, I think that they use these to replenish health, so I also give my companions one food item.

On the PC, you can set them to essential but that means looking up their base id for them and maybe their guards and Brahmin, and then they can still go unconscious.

Some mods do make them essential and/or give them more and better equipped guards.

But I think the simplest way on the PC, is to increase their health using the console command "setav health " Just open the console with tilde, click on the merchant, guard, and/or brahmin and enter that command. I tend to give them about 3000 to 5000 health.