Nobles, the best way is to not raid whatsoever, keep anarchy super low, I also found it easier to treat with the nobles if A) You don’t stop the harrowing whatsoever, or B) convince the rebels to inflict zero violence during the rising (But this way requires 2CHA if you’re nobility). You will start seeing an effect during spring. It’s also much better to actually be nobility. If you are nobility then you can have ties through cousins and family and end up with alot more choices to parley and speak to them. If you’re a helot, then it’s practically impossible to recruit the nobility. They’ll just look down on you.
As for priests, someone seems to have said above about how to do that. Merchants, I found once again, super pacifist and then convince Alaine to trade with you (MAKE SURE YOU HAVE ENOUGH MULES TO COMPLETE THE TRADE WHEN IT COMES, which is at least 7 free on week 5/6 I think.) She will call off the deal immediately if anarchy gets high.