If I kill everyone in the Zhentarim hideout in Act1 will the faction become enemies?

[noisyturtle]

Will doing this make the vendors attack me elsewhere, or once I reach BG?

[Fluff]

They aren't really your allies to begin with .

But no, dead can't speak unless you Speak with Dead on them , so nothing tragic like that happens.

[Forblaze]

It has no future consequences.