From my experience, I hate PVP on NWN, why?
Because mechanically speaking is awful. Most of the time the winner is the one first to strike or the one who was most buffed.
Also, I don't build my toons/gear to have max AB, AC, Saves etc etc etc just to PVP, so most likely in PVP I'll go down in one hit or two. Flawed characters are the most fun to play.
So, when I get killed in two hits, I wait 5 minutes in limbo, go to some tavern and RP the wounds and.. well, depending on what happened try to follow the "I don't remember what happened too much" event and just be annoyed that someone completely interrupted my play session with penalties for x hours and just log out for the night as sadly on Arelith getting killed in PVP means your toon suffers penalties that can't be dodged / healed.
In some cases, I tried to RP these cases, but, it always have been an awful experience and the trigger to start PVP is something very silly, I once experienced a PVP because a one line from a drow "I don't like your elven friend *attacks". All the antagonist I met seems to be quick trigger players, shot first, ask questions later.
Sometimes I don't even finish writing a sentence and the battle already started. Other times, I did not even had a chance to say a line and the battle started. There was an event the whole "RP" was in draconic and my toon didn't knew the language and ended dead.
For example, my last two experience with an animators:
A) A group of 5 players runs passes shouting "We are in a rush with a dead friend, MOVE", we were two, the other toon I was partying says "animators.. pathetic". Then they set us to hostile, runs back half a map and starts attacking / chasing us for 2 maps. They RP was "MOVE WE ARE IN A RUSH TO REVIVE OUR FRIENDS", but just the word "pathetic" caused them to forget their RP completely and start attacking us. 5 vs 2.
B) Another one was just last week, as soon as I saw the guy with zombies, he starts buffing. No words, no RP, nothing... Sees me.. starts buffing for 1 minute, then their summons and once he finishes he starts RPing saying "What do you want?"
I have never experienced any antagonism RP where I could even RP, neither they offer me the non PVP "you lose option". As soon as "conflict" arises, the other side just start buffing without even crossing 10 sentences, types !, and attacks.
So, even if you want to RP antagonism / PVP, the other players also have the option to flee. Is a total valid option to do. Just like in real life, when there is a robbery in a store or there is a gun shot. Do people bothers to talk to the bad guy? Most of the time everyone just hides or runs. Why would be different on a RP server?
Also, you don't know what the other player scenario is, is he powerful enough for a battle? are all their spells / wards up for a battle? Are they carrying a large amount of coins? Were you fully warded with an horde of summons along you while the other was not? Maybe they are a commoner and just wants to run. Maybe they thought you weren't alone and 10 archers where hidding in the bushes. Maybe they really wanted to play that toon the next 2 hours and getting killed would mess with their play time.
Finally, even if someone plays a good character, it does not mean he's a paladin that HAS to fight an evil-doer.
Running away is and should be always an option available in my opinion.