Is there any reason not to kill the Nevon who give you quests?

[balkroth]

I've done two now, getting the weapon back for diver guy and giving the flesh of the big guy to the little guy so he can become a big guy. I've left both alive in fear of missing something later in the game, so can I kill them? Or are there any I can't kill?

Thanks in advance.

[Moriendor]

Yes. You get an achievement for helping each and everyone.

[WZ]

there is a good reward for sparing them all yes : 100 colour of lumina
you can go back & butcher them afterwards if you really want, but why?