There are a bunch of Xaurips around the sacrificial pit.  They don't go hostile.  Am I supposed to attack them?  Is there a reason do (not) so?

 

There is also the Xaurip on the same level that is sick or something, and you have a choice to slit its throat.  Any reason to keep it alive?

LOL, I asked the latter question a couple of days ago. I received no response. I kept him alive in hopes something revealed itself down the road.

 

As for the first part, there's a high priest on the other side of the pit that, when revealed, triggers a pre-combat dialogue.

Yeah, what is up with that sick Xaurip? Does it require a high Lore or Survival or something?

Thanks guys.  I went ahead and attacked the group.  I don't think I got the speech, but I may have.  I left the sick Xaurip alone.  It is not going anywhere.

I killed it. Sagani and Eden seemed to approve

yeah, I saw something pop up like a journal note when i ran into the high priest, but i was already too busy killing the roomful of lizards to see what it was it said.

if I had actually waited to attack until he said something... I think I'd be dead.  that actually was a pretty tough fight on hard.

 

The only thing the High Priest says is "Get in the pit." Then he attacks you. As far as the dying xaurip, you can't save him as far as I've been able to find out. You can either leave him to suffer or put him out of his misery.