Unfortunately with mods like Skyrim NPC Immersion Mod, Deadly Dragons, Occupy Skyrim, and Wars IV NPC's quest giver's get killed. Therefore truncating quest lines. So I propose a mod that flags some vendors, quest givers, and unique citizen's unkillable or something depending on the situation or the progress of a quest.

So when the quest is completed the characters involved in them become non-essential (killable) Of course some special cases need to be made for NPCs who need to be killable for certain quests. It would really be nice to find another way besides flaging NPC's essential but I personally can't think of an elegant solution. What are your thoughts on how this should be implemented and is anyone willing to take the mantle?

This is something that the creator of each mentioned mod should do.

I'm thinking of just protecting vanilla. Although it would be neat to see some sort of tool to scan and protect quests added by mods.. but that's a little far-fetched.

Making NPCs protected - which means that attackers will cease to attack them when they go down to 0 unless they're the only target around - might do the trick.

I disagree; none of the above mentioned mods have anything to do with the default behavior of Bethesda-made quests.

A mod like this would unfortunately be a bit tedious to build, as you're going to have to go quest-by-quest and SetEssential particular NPCs depending on the quest stage. It's possible to do this in such a way as to not cause a conflict with other mods that might modify that quest by simply running a script in the background that does a GetStage on (perhaps many) quests and performs SetEssential operations as necessary. This would be performance-intensive however. The other option is to edit the quest fragments of these quests and add the SetEssential lines as necessary there, but any other mods that edit those fragements would be incompatible. I don't know if other mods (USKP?) made modifications to these fragements for bug-fixing purposes.

I think the idea has merit however and should be investigated.

True, but. Just batch editing most NPCs in towns to be Protected would be faster and less arduous. Also lets the player continue to kill NPCs that they wish to.

Wouldn't it be easier to have a local script forcing NPCs to yield and flee to indoor locations when fighting enemies they can't possibly beat? There is a mod that accomplishes that (Fight or Fly), would be a matter of expanding the conditions to include things like vampire attacks (in Dawnguard), dragons and civil war battles.

You're right and to some degree they have. They have done their best not to mess with the vanilla quest lines themselves but I have seen no safeguards in place that protect the MPCs that give out quests. Really it's not one mod thats the problem. It's the the cumulative effect of running them all at once.

The best solution is the kind that has the least impact on the player. I think setting NPC's to essential is intrusive. So setting them as protected seems to be the best solution presented at the moment. As on how to implement that is another question. Modifying the quest that through the CK seems like that only a lot of work but would introduce potential compatibility issues with anything that alters vanilla quests. That leaves us with some sort of fancy script to dramatically alters quests as the player advances in the game. Which could be potentially resource intensive.

Another aspect that hasn't been covered would be to extend a concept that Bethesda has already implemented. A example would be if the shopkeeper was killed a relative would take over the shop in their place. I would say the majority of quests outside of the main quests could actually have the same thing done to them. This approach would take a lot of work but by far with the most immersive if done correctly. In addition there were be no performance penalty and I think maintain compatibility. Someone with more knowledge and experience of how Skyrim quests are created and executed in the game will have to speak on compatibility.

or you cna just use this http://skyrim.nexusmods.com/mods/11977

saw it in a similar topic on another message board, so i dont know how well it works.

Wow, reading the description it looks close to OP. It looks like author has gone through an edited NPCs to make them essential. Reading through the comments it seems people are having problems completing quests because NPCs have been made essential whom need to be killable for certain quest.

It is a start to solving the problem. Although I'm hoping we can think of a more elegant solution.