Beginning game spoiler alert...

I have Fane in my party and have tried approaching Kniles the Flenser with him alone, as well as with every other member of my party and he always just outright attacks us.

I want to give him Atusa's leg so that we can avoid the combat, and I have it in my inventory but there is not a moment when I can give it to him before combat!

Is my persuasion not high enough? I am confused as to why I cant speak with Kniles at all, he only calls me out for being an intruder and I have to click "End".

Thank you everyone in advance for your help. I really want this face ripper but I don't think I can beat Kniles.