maximaz
Sonny, I Watched the Vault Bein' Built!

finds his sister
I know that he was meant to but it's been cut and unofficially patched, but the fact that you never come across her in the finished game is very fitting to the setting.
She vanished without a trace, possibly an unremarkable slave who died during a trek across the wasteland somewhere, maybe made a run for it and got shot and was eaten by rats in some basement or wandered into an irradiated zone and fell ill and died in the middle of nowhere.
Fallout 1's wasteland felt like a dark unknown where anything could happen for one to disappear.
That is all.