What are you comfortable with based on your role? I've had Tribs where I don't kill goodie Outlanders, I've had goodie Outlanders that don't kill goodie Tribs, and I've had both that don't hesitate to kill either because the true evil in Thera is Chaos/Order depending on your views.
If your character is a pacifist nobody is going to uninduct you for not hunting down and murdering goodie characters. In fact, you don't even have to actively defend the cabal. Its expected that you try your best to do what you can to heal huntress if possible though and you need to go retrieve.
As far as hunting Reavers, feel free to kill them any time outside of a defense/raid situation and never inside the tree. They can't hunt you during these times either.
Make sure you're chaotic, I wasted the best ranger role on a non-chaotic Outlander because I didn't know you lose windwalk. lol
Also you don't have to actively hunt thieves/assassins.
Review your backstory/role. Put yourself in your characters shoes. How would you react in all these situations if this was real? Do that in character. Its all very fluid.