Here's the situation: I use a mod that adds a book near the great oak of Chorrol, but strangely this time the book was no where to be found. Using a test character, I confirmed that the book is there at the very beginning of a game. My conclusion is that an npc must have stolen my book! But I have no clue on who the culprit could be. So, who's the biggest thief of Chorrol?

Maybe it fell through the ground. I've seen one of the guards stuck waist-deep in the raised ground around that tree, struggling to walk out.

This was my first thought too.

NPCs in Oblivion are given Responsibility in the form of a number between 0 and 100. If their Responsibility is below 30 they are, under defined circumstances, capable of stealing. What they steal is dictated by an AI Package. If an NPCs AI Package requires them to eat food and their Responsibility is lower than 30 they will steal food. If that NPC does not have an AI Package that instructs them to eat they will not steal food even if their Responsibility is 0.

As far as I am aware, no NPC in the game has an AI package that instructs them to go in search of a book. So I would be very susrpised if any NPC in Chorrol stole it, unless it was an NPC added by a mod.

Would the same apply if the book wasn't marked as owned, though? I don't really know much how it works, but I remember Renee once saying she thought one of the Jemaine brothers had taken a sword she dropped on the ground. It might be different with books though.

My first thought was maybe it dropped through the ground. In the Leyawiin house once I dropped something on the floor and it fell through it.

That's an interesting question. I'm not sure I know the answer to that. If the book was unowned, Responsibility wouldn't be a factor. You've stumped me. I don't have the faintest idea.

I know that NPCs are "programmed" to pick up a better weapon. I used to drop Iron daggers in front of Goblins in the tutorial dungeon so that they would pick it up and hit me with it instead of using their fists (This was a powergaming cheat on my part: Goblins did more damage with their fists but the game didn't recognize that. The game only knew that the Goblin was unarmed. So it made the Goblin pick up my Iron dagger. The Iron dagger did less damage to me and as a result I got hit more times with it and suffered less loss of HP and leveled up my armor faster.)

ANYWAY, back to the subject - so I'm thinking it's possible that the Jermaine Brother picked up the sword as part of this hard-coded AI all NPCs are equipped with. The question is, does this hardcoded AI behavior apply to books as well? I frankly don't know. I've run up against the outer barriers of my knowledge of Oblivion AI mechanics. My brain is telling me "You cannot go that way. Turn back."

Meh, if there wasn't a script involved, I could just console myself a new copy of the book. Oh well, I'll just start over my character. I wanted to change a skill or 2 in his build anyway. Thank you all for your input.

Some NPC's do have read packages though. But as far as I know, they all have books already. Maybe, if one happened to have a read package and didn't have a book in their inventory, they would pick one up. But there's an awful lot of books sitting out in shops and guildhalls and homes, that I've never seen disappear. Seems a remote possibility. Stuff falling through the floor happens all the time though.

Using the console, move yourself to the book. That will answer the question of whether if fell, or was stolen. You can just as easily coc or tcl or whatever afterward to get back to where you came from.

In the case of Dyan and the Jemane brothers, What happened was this:

Dyan goes into some fort on the West Weald, but leaves the Jemane brothers outside. she also dropped the Sword of the Crusader on the ground, because she already had a suitable weapon.

Again, she dropped it on the ground. And outside...out in the open.

When she comes out of the fort, the Jemanes were in the midst of battle with some undead. One of the brothers either broke his weapon, or perhaps it was an enchanted weapon which lost its charge. I'm thinking it broke, though. It's impossible to take an NPC's weapon to try and get it repaired without "stealing" it., which means the Jemane's weapon broke, more than likely.

The Jemane brother sees the Sword of the Crusader on the ground, and snatches it up.
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