These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Riftwar Cycle
Complete Monster: Murmandamus is the Big Bad of Silverthorn and A Darkness at Sethanon. A Pantathian serpent-priest who plans to bring the long-banishedValheru back into the world, Murmandamus disguises himself as the reincarnation of the moredhel's (dark elves) greatest leader, uniting the mountain, forest, and hill clans in a campaign of genocide against their human and eledhel enemies. He sends assassins after the Prince of Krondor, which gets numerous people caught in the crossfire. He steals the souls of his human servants in a ritual that involves sacrificing a nine-year-old girl. He creates the Black Slayers, soulless moredhel, bound in service to him forevermore. He murders a seer who gave him the information he wanted, and massacres hundreds of slaves when he realizes that his campaign isn't going to start when he wants it to. In A Darkness at Sethanon he destroys the cities of Armengar and Sethanon, lines his headquarters at Sar-Sargoth with a thousand human heads on pikes, kills hundreds of his own men in a fit of rage, tramples his right-hand serpent-priest, Cathos, to death, consumes the souls of all those who have died aiding him, and in the end, tries to activate the Lifestone, an Artifact of Doom that will slay all life on Midkemia from bacteria to humanity, in order to loose the Valheru. Believing that he will attain demigodhood when the Valheru return, Murmandamus dies laughing about how "I am a thing of death, Lord of the West. I am ever the servant of Darkness."
Esoteric Happy Ending: At least for thousands of people from Midkemia in Riftwar Saga, who ended being slaves of the Tsurani during the invasion. Is not stated what happened to them and by Pug POV (and the statement of Asayaga) they either ended in hellish conditions dying like animals or as a sex toys of the conquerors. You know, a happy alliance between worlds.
Later books (in particular The Empire Trilogy and the circumstances of Kevin leaving Mara's service) seem to indicate that a prisoner exchange and release of Midkemian slaves back to their homeworld followed.
Idiot Plot: A last-minute plan change in Shadow of a Dark Queen arises when Roo remarks that the Emerald Queen will need to build a new armada before she can send an army halfway around the world, and Calis and company decide to try destroying Novindus' biggest shipyard to put her back several years. Until Roo spoke up, nobody thought to ask where she would get ships of the size and number she would need to carry out her inevitable invasion.
To be fair, everyone was so focused on not dying that they didn't have much time until then to stop and think.
Mary Sue Topia: The eledhel in Elvandar. They are all morally upstanding, all beautiful, all skilled. Their very home is a work of art, the mere sight of it sure to drive the most grizzled veteran to tears. They harbor no resentment for anyone, regardless of reason. Any elves who don't live as they do are considered unfortunate deviations from the ideal (as the term "The Returning" implies), but are generally happy to abandon their whole life's worth of teachings and values (and, in the case of the moredhel, family and friends too) and go live with the eledhel as soon as they realise how awesome they are. The glamredhel literally skip off to Elvandar as soon as they learn it exists. And of course, moredhel can go "good" and become eledhel, but no eledhel ever goes bad. Ever.
There is ONE character in all the books who's been to Elvandar and has anything negative to say about it: Calis, Tomas and Aglaranna's son. He considers its static, unchanging ways to be "boring" and vastly prefers human company.
The Problem with Licensed Games: Avoided, as Betrayal at Krondor received critical acclaim and Feist liked it enough to novelize it personally. He even transported some of the game characters into his later books.
The Scrappy: Prince Patrick. He's an arrogant spoilt brat who rules over the Western Realm and is clearly unfit for the position to the point that no one really seems to like working for him and Pug can barely tolerate him.
Pug conDoin, The Hero of the overall series. Despite his amazing powers, he was cursed to see everyone he loves die before him due to a deal with the Goddess of Death. All of his family and closest friends die and he can do nothing but watch it happen. The only life he's able to save is his son Magnus' due to a fluke on his part as well as a deal with the gods to die in his place. Basically, Pug's life sucks.
Pug's son, William conDoin's life sucks too, but not as much. He sees two women he loves die, the first woman is also heavily implied to have been raped before being murdered and dies in his arms. The second woman is who he considers his One True Love and he has to Mercy Kill her since she was possessed by a demon and it would have been impossible to save her. Thanks to these experiences, William gives up on romance forever and dies alone in the Serpentwar.
James Jamison/Jimmy the Hand is an Iron Woobie. He grew up on the streets after watching a drunken sailor kill his mother and once he becomes Arutha's squire, he goes through alot of physical abuse throughout his life and sees alot of death and horrible things and nearly dies a few times. Not once does he complain beyond snarky comments here and there. Luckily his determination pays off as he meets Gamina and they have a long and happy life together until their deaths.
Nicholas conDoin, Arutha's third son. Mocked endlessly behind his back due to his deformed foot and bullied alot by his elder brothers he admired. He doesn't have much in the way of confidence as a young adult and when he has to kill for the first time, he's pretty horrified.
Erik von Darkmoor's surrogate sister Rosalynn. She's brutally raped by Erik's half-brother Stefan and ends up pregnant with his child. She probably found closure in the form of Erik killing Stefan though.
Eye of the Blue Winged Teal, or Teal for short, aka Talwin Hawkins' wife. Kidnapped when the Orosini were practically wiped out as a fifteen year old girl and raped endlessly until Talwin finds her when they're in their mid-late twenties and has a child from that rape who Talwin raises as his own. She's stated to never fully recover from her traumas, but she recovers enough to be Happily Married with Talwin and have another son.