Keep it cool guys. Also thanks for the info, everything is very helpfull!
NPCs; Character-istics
What do we know about NPCs? Or more like, what do we think we know about NPCs?
The fact is the no one ever really cared about NPCs, and with introduction of the "light blue" shit into the interaction with them, people have turned even lazier than before, people underestimate the mechanics of NPC; we're all used to goin' into Wiki and do everything as expected, to interact the least possible in order to move on to the "fun" parts of the quests.
What do we know? Truth is we dont know shit.
We can just especulate, and that's the fun/tricky part, but here is what we know for sure:
The way they're dressed sometimes plays a role or gives you a clue (outfit quests).
NPCs not just react when you repeat "light blue" entries, but to the contrary, they react to so much that the possibilities are endless.
NPCs react to items, "NO SHIT!?" right? well, it is a little bit more complex than that; NPCs not just react items that are needed for quests (where you have to actually lead the conversation into the item so it can be exchanged) NPCs also react to items that are in your backpack WITHOUT acknowledging their existance THROUGH a deep conversation, check this example:
Without Garlic Necklace in BP/Equiped:
With Garlic Necklace in BP/Equiped:

U might think this is just a clever little detail CIP may have added to the interaction of this NPC, but it means SO MUCH MORE:
What this actually means is that what you have in your backpack AFFECTS NPC REACTION, have you any idea of the endless posibilities there are?! This means everything is possible, this means that if you so happen to have the right item, with the right NPC, saying the right words, this could lead you to a complete 180° turn in the conversation; taking you to a brand new quest OR valuable piece of information that might be usefull later.
IMHO I find this just as fascinating as it is discouraging and here is why; take the 552 NPCs that exist in Tibia, now multiply that by the number of items that exist in Tibia ATM, now multiply the result by the INFINITE fucking number of keywords (not necessarily "light blue") that makes NPC react, yes, that's right, that equals: ∞.
Shit . Just . Got . Real!
I chose that particular example above to prove my point, for a reason; Vladruc has been around since 2002, and he has been reacting to a Garlick Necklace since then, than means that AT LEAST since 2002 this item-conditioning; has existed.
With this in mind, and taking into account that not even Maurolkit (EK Level 658) with his 16720 cap; could carry enough shit to be 100% sure nothing slips by on a conversation with an NPC: the worse enermy of Roleplayers, also known as: "Why bother?" returns to haunt us.
And it is true, this is IN FACT discouraging, but I believe that in this world everything is relatevely proportional; Work big and big you shall be rewarded, and seriously guys, do you have any idea how much items as lousy as "Blood Orb", or as legendary as "Crown", or even as recent as the new "Snake God's Sceptre" (which in-game existance has been made publicaly by Mirade) are worth? Plus, the glory for finding them first is priceless.
But enough of this deliriums of greatness, lets get back to the topic.
A good example that I can think of when it comes to item-interaction is taking a Bonelord Helm & Shielding and start blurting number patterns to our beloved "Blinky" why not? 2 eyes of your own, 2 of the Helm and the one in the shield, sounds retarded? maybe, or maybe not, truth is no one can really tell.
The above info is just 1 of the many improvements CIP has done to NPCs over the years, to make a completely reliable list of NPC changes we'd have to go through every Quest-related NPC's reaction/mechanic/association, etc, then take them all and asume that every NPC in Tibia is capable of such behaviour, regardless of their introduction date (since even old shit gets updated) or the function that we suppose it was created for.
So by this premise we can begin to conclude that everything we think we know about NPCs is out of date, and changes in every major update.
It just gets worse and worse eh? Remember guys, it's always darkest before dawn.
When I do more research in the NPC-Behaviour department I will post a second part of this subject and provide a link in the 1st page of this thread for easy access, remember to check it regularly for updates and remember that the beauty of this subject is that there's no stupid ideas, anything goes!
Atheist.