Part 2: Lore Dump 1
Update 02: Lore Dump 1I'm trying to keep each of the lore dump subheadings somewhat concise because... goddamn, nothing in the Midkemia books is ever simple and concise. Thanks to time travel there's rarely ever just "a beginning" and the chronological start of things is often explained midway through the second book in a two-book sub-series. Let me know if you want me to ramble more about a particular subject, because Christ will I not run out of material any time soon.
Locklear
Locklear first appears in the third book, Silverthorn, where he and a young Jimmy the Hand have ended up as squires at Prince Arutha's court. They end up fast friends as Locklear is, himself, not the son of anyone important enough to put him high on the pecking order and he's impressed with Jimmy's street wits and the fact that he doesn't take shit from any bullies among the other squires. When Prince Arutha and his friends end up setting off on a top secret mission to save Prince Arutha's wife(who got hit in the back by a poisoned crossbow bolt during the wedding), Jimmy and Locklear figure out something's up and invite themselves along, almost getting killed along the way several times.
After Princess Anita's life is saved, life goes back to normal until the fourth book, A Darkness At Sethanon. Once again, Locklear and Jimmy end up accompanying Prince Arutha on a dangerous expedition, this time into the Northlands, the heart of Moredhel power, where they end up in the besieged, militaristic city of Armengar. When the city is overrun, a girl that Locklear struck up a relationship with is killed by the invaders and he turns out to be a pretty dangerous fighter when he's sufficiently pissed off by an event like that. He ends up surviving the siege along with the other main characters, joining them in their rush to Sethanon where he ends up protecting more women in a besieged city when the walls come down. This time he succeeds, however, and most of his reputation as a ladies' man is from when the partially collapsed basement is excavated by the relief troops.
The Tsurani
The Tsurani are the Aztec/Japanese melange culture which are the apparent antagonists of the first two Midkemia books(Magician: Apprentice and Magician: Master). They appear out of nowhere and lay siege to the Kingdom from within its borders, displacing Moredhel, threatening Elvandar and having no apparent end to their troops. The protagonists later realize that the Tsurani are being teleported in from their own world, Kelewan, which mainly differs from Midkemia in being much hotter and being much more poor in metals. The invasion of Midkemia is pushed by two things: the hunger for Midkemia's metals(which are insanely valuable on Kelewan) and political pressures(the Tsurani warlord has been backed into a corner by being unable to find anyone to persecute a war against for a while), and to maintain his political power he latches on to the idea of invading the Kingdom of the Isles.
Most information about Tsurani history and culture are related when Pug, the main protagonist of the Magician novels, is captured at the end of Apprentice and spends several years as a Tsurani slave in Master until the Tsurani discover he has magical talent and elevate him to the role of one of their Great Ones(unlike in the Kingdom, there's no such thing as a wizard of low station among the Tsurani). A lot of magical bullshit later, the rift between Kelewan and Midkemia is collapsed, and the surviving Tsurani on the Midkemia side are made freemen of the Kingdom. Eventually, during A Darkness At Sethanon, the Rift is re-established, and from then on, Kelewan and Midkemia enjoy largely peaceful trade relations as the Tsurani Emperor, Ichindar, has no desire for war.
If you dig more into the DEEP LORE, the Tsurani are humans, just like the humans of Midkemia are(aside from whatever genetic drift happens over thousands of years of interstellar separation), due to an ancient disaster that destroyed whatever was humanity's ancestral home. But explaining that, or why the Rift had to be blown up once, and during a peace conference at that, would require explaining the Valheru and Macros the Black and... hoo boy, we're not even a quarter of the way there yet. Suffice to say it involves multiples of time travel.
The Tsurani are largely respectfully handled, with perhaps a bit of exoticism, and the occasional bit of heavy-handed "the Kingdom's pseudo-European meritocracy is a superior system of governance to the Tsurani's largely clannish, fundamentally primitive system of government.
" but the Kingdom is also shown to have its weaknesses, with insane kings, internal politicking and so forth.The Moredhel
Possibly unique among fantasy dark elves, the moredhel are almost physically identical to their non-dark brethren(the Eledhel, who live in the Green Heart), and their differences are instead largely ideological. When the Valheru empire collapsed, their slaves, the elves, split into two* factions, the Eledhel, who realized the Valheru were dangerous psychos and just wanted to live in peace, and the Moredhel, who thought the Valheru were on to something and wanted to reclaim all their ancient magic WMD's and rule the world. This also informed their reactions to humans, the Eledhel see them as fellow sapients, while the Moredhel see them as usurpers of Midkemia's lands and resources. During the Magician books, the Moredhel are largely a secondary danger, since they primarily raid around the edges of the action and are as threatened by the Tsurani as everyone else on Midkemia.
During Silverthorn, however, they've gotten themselves a prophet, Murmandamus, who uses force and manipulation to unite the Moredhel factions into a single unified army that he leads against the Kingdom with blatant disregard for the lives of the soldiers under his command, slinging around ridiculous magical powers with little effort and largely seeming invincible all throughout Silverthorn and A Darkness At Sethanon, two books during which the moredhel largely seem to be completely insane beings composed of nothing but anger, murderousness and political jockeying. Betrayal at Krondor represents the first time we see one of them displaying positive emotions, making jokes, cooperating with humans that aren't greedy weapon-runners or mercenaries, etc.
Of course, Murmandamus turns out to be a fraud(a shapeshifted lizard alien, literally, I'm not even joking) and he almost manages to end the world by fucking with stuff he finds underneath Sethanon, but he gets stabbed at the last moment, which collapses the Moredhel war machine entirely. The Moredhel in Betrayal at Krondor have suffered insane losses in recent history, literally entire generations of Moredhel have ended up dead or maimed and they are distinctly on the back foot, they absolutely should not be a threat any longer.
*Or so we're told during the Magician books. Of course there aren't just two kinds of elves, no author who starts introducing multiple brands of elves ever stops at two. You fool, you absolute rube, you will drown in elves of every kind.