What happen to them and the people you meet fighting out side Nipton, do they just dissapear or go to a specific place.
And what happens to traveling merchants and prospectors when they are killed.

PEACE

Oliver Swanick will run off into the desert just southwest of where you meet him, where he'll likely be killed by radscorpions.
Tomas and Malcom Holmes will walk to the NCR border.
Not sure where the lady goes cause she always turns on me.


But basically the NCR Outpost border is the go-to for NPCs leaving the game world.

so i might as well kill them

What a lovely rationale.

Is this how you think in real life, too?

Raynor Johnsson: (points to garbage man) "Hey, what does that guy do after he's done throwing everyone's garbage into that truck?"

Random Guy: "Erm... he drives back to his house and goes to bed?" >_>

Raynor Johnsson: "So I might as well kill him."

It's a bit of a solipsistic way to live, but you'll have a wonderful career as a prisoner.