You must have explored the game more thouroughly than the entire fanbase combined.
I wouldn't say that, I just don't invent fanfiction to make up for Japanese writing's shortcomings, unlike the Dark Souls fanbase. This phenomena wasn't present with Demon's Souls as far as I can remember, but it's a disturbing trend that I absolutely fucking hate, but then again, Demon's Souls actually flushed out most of the NPC's so there wasn't a need for the emotional/feminine fanbase to just start imagining up bullshit endings to unfinished characters.
As for the NPC's who either had their motivations stripped from the final product, or have none to begin with, and are inconsistent, i'll list a couple:
Shiva of the East, Oscar, Paladin Leeroy, King Jeremiah, Witch Beatrice etc.
If you want me to get in to specifics about the bad fanfiction, Kirk of Thorns is probably the most appalling example. Here's a guy who's sole existence revolves around victimizing other people for their humanity, and through in game lore only, he's presented as a complete psychopath. Well, from what the retarded fanbase has said, he's secretly working for the Chaos faction, and he's really just killing everbody to give the humanity to the spider, even though there are no in game references to Kirk from either the eggback or the spider herself. Kirks body at the Chaos bonfire could mean a million different things, but not to the fanbase! To the fanbase, it means Kirk is really just a poor, misunderstood, anti-hero, who really cares about life, despite him wearing poky armor and him constantly trying to kill you. You would think a betrayal to the Darkwraiths and a conversion to Chaos would be mentioned by Kaathe, the eggback, or the spider, or even his armor and weapons, but mysteriously enough, it isn't.