Vault 73 was once a sealed community subsisting only on what they had been allowed to bring in before the war. Many generations passed before scarcity caused social unrest culminating in the assassination of the Vault overseer, the opening of the gate and the eventual construction of Fort 73 on it's doorstep. Initially wary of anyone from the surface, the dwellers gradually began to benefit from barter and mutual interest and by present day the exterior building known as Fort 73 has grown to become a minor trade hub with access to the Vault, it's growing resources carefully managed by a new generation of dwellers.

Vault Generation & Stats

Name: Vault 73

Vault Population Table

d: 1d20=17
-> Mixed Community: The doors were opened years ago, or else they were bypassed to allow traders and new blood into the settlement. 
-> Truths: Trading hub, Initiation Rites
=> The original story of the Vault Overseer being murdered, subsequent upheaval and the opening of the doors (by the murderer?) can still be used here. I would just kick the can down the road a bit and have Gwendy be the offspring of a mixed Vault/Wasteland pair. The area around the vault is a trade hub, but access to the inside is strictly forbidden for non-citizens.

The Vault population is 90% descendant, with a 10% slice of outsiders who have proven their worth and taken the rites citizens swear as they come of age. These outsiders are trusted as fully as a descendant and have all the same rights and privileges.

Maybe there were a few Pre-War Pioneer Scouts taken into the vault who maintained something of that tradition down the generations until it acted as a sort of moral DNA expressing in a dutiful protection of ones own (and the Vault) balanced against an optimistic compassionate streak. Looking for the good in the bartering wastelanders is what lead to that special 10% subset.

Vault Reputation

d: 1d20=18
-> Friendly: You are on good terms with your former neighbours, and they are likely to help you in your endeavours. 

Vault Dweller NPC

d: 4d20=18, 7, 16, 10
-> Name: Holden
Appearance: Hollow-cheeked
Personality: Dutiful
Vault Position: Radio Operator

Vault Experiment

I was originally going to select Control Vault instead of rolling, but I just pulled Treasury and it kinda jives with 73 being a trading hub. It could be rumoured to contain treasures, but what they are specifically may not be what people expect. Pre-war, useable as barter goods...

Tidbits

• In Session 7 Gwendy recollects how Old Man Percy told her (and anyone else who'd listen) that overindulgence in alcohol led to the end of the world.
• Gwendy claims that a devastating Rad-nado nearly destroyed Fort 73 some years back, prompting the vault's ruling council to enact safety measures.
• A cunning and dangerous rad-wolf known as Sawtooth terrorized the trails leading to the Vaults surrounding gully a few years before Gwendy was born. Jennifer and Nate Corner took it upon themselves to run it down, a job that was ultimately completed by a cave dwelling Yao Guai... not unlike the one that attacked Louise Powell.