The idea is basically to expand the features of the base homesteader to something more customizable, I don't expect this implemented anytime soon (if at all) but the idea stands anyway.
The caps would be taken from the base leader's bank account, or anywhere else like a random container or whatever, doesn't really matter that much.
Keep in mind that none of the information give in these NPCs is supposed to the be fixed product, all numbers and possibilities are simply an example of what I have in mind.
To make things balanced, one could put a limit to the number of NPCs in each base to avoid overflooding and abuse.
Universal NPCs that can work in any base:
Homesteader
Price: 800 caps a month.
Location: Homesteader encounter, need to convince one to work for you.
What it does: Basically the same it does now, I thought about picking items from the floor and placing it into containers but that probably wouldn't work well.
Guard
Price: 700 caps a month.
Location: Merc seller, ask for guards for your base.
What it does: Protects base from uninvited players.
Strong Guard
Price: 1500 caps a month.
Location: Merc seller.
What it does: The same as a guard, only a little better since he's almost as strong as the default human mercenaries.
Tenant
Price: Gives you 250 caps each month.
Location: Homeless people encounter.
What it does: Occupies space, may misbehave and steal some of your items if you don't put enough guards into that base to keep the order (around 1 guard per 5 tenants or 1 strong guard per 3 tenants).
Nurse
Price: 2500 caps each month.
Location: Redding, talk to the doc about hiring someone.
What it does: Heals crippled limbs.
Brahmin Boy
Price: 500 caps a month.
Location: Talk to any brahmin herders about hiring people.
What it does: Keeps the shit pen in your base, this NPC never leaves the shit pen to avoid the brahmn from escaping.
Fixer
Price: 1200 caps a month.
Location: NCR, talk to a mechanic about hiring people.
What it does: can craft low tier stuff for you, however, this NPC will only use materials inside the workbench of the base so he won't work in a trapper camp.
Slaver
Price: 2500 caps a month.
Location: Den, talk to Metzger about hiring people.
What it does: Brings slaves and gives them to you, this NPC will only be available if the leader of the base is a slaver, the amount and kind of slaves he brings is random but is never higher than 8.
Messenger
Price: 200 caps a month.
Location: Den, talk to one of the homeless children about giving him a home.
What it does: asks for a holotape, once you've given him a holotape he will ask who he should send the tape to, he will eventually find the player he's supposed to send that tape to, say something like "Playername told me to give you this, Mister!" and run back to your base, this NPC would pretty much teleports to the player who's going to receive the tape.
Base specific NPCs:
Mechanic
Price: 3000 caps a month.
Location: New Reno, ask T-ray about hiring a mechanic.
What it does: Any cars parked in his base will slowly be repaired and refuelled, around 1% repair/refuel every 5 minutes.
Can only be in: Gas Station.
Doctor
Price: 5000 caps a month.
Location: Vault City, talk to the doctor inside the vault about hiring.
What it does: Cures radiation.
Can only be in: Old Bunker.
Barman
Price: 1200 caps a month.
Location: Vault City, talk to the unhappy barman about a new job opportunity.
What it does: Sells you drinks for the same prices the other bars in the wasteland do.
Can only be in: Scraphead.
Tribal
Price: free
Location: Nomad encounters, talk to them about following you to their new tribe.
What it does: Occasionally gives you some tribal stuff like rocks and healing powder, does not revolt like tenants, he is pretty much an RP NPC.
Can only be in: Trapper Camp.
Repairer
Price: 8000 caps a month.
What it does: fixes any items you leave in the workbench, however it takes time, repairing an item from 1% to 100% would take roughly a day.
Location: The small gun expert in Junktown, talk to him about hiring someone to keep your equipment repaired.
Can only be in: Depot.
Scout
Price: 10000 caps a month.
What it does: finds a player for you, after coming back he will tell you the player's exact zone, you have to wait 5 minutes for the scout to come back, however.
Location: Merc seller.
Can only be in: Cave.
Security
Price: 1500 caps a month.
What it does: same as strong guard, except that this one will only start eating population space once you have 5 or more of these, that allows you to use your population limit for something else while keeping the base relatively secure.
Location: Merc seller.
Can only be in: Outpost.
That's pretty much it, and before someone complains about Tenant prices being too low compared to other NPCs, he is supposed to only lighten the upkeep in bases with leftover population space, it would be too easy to just build tons of bases filled with tenants.
The dialogue of each base NPC would be something like this:
<Job-related dialogues>
I want you to work somewhere else. (sends NPC to other in another base)
How are you? (NPC happiness depends on number of guards protecting base)
You're fired.
Nevermind.