Chronologically, The Spellcoats takes place first, during Dalemark's prehistorical period. Cart and Cwidder and Drowned Ammet overlap somewhat, but Cart and Cwidder generally comes first, as its events are over before the action really starts in Drowned Ammet. The Crown of Dalemark takes place last.Each book has a different protagonist, although all of the characters appear in the final volume, The Crown of Dalemark.
Tanaqui - Named after the scented rushes that grow on the riverbank. Has four siblings named after birds. Skilled at weaving and able to use magic through it. She and her siblings are chased out of their village and escape by riverboat, which leads them into an encounter with the king and draws them into the struggle against an Evil Sorcerer. Her father was married to one of the Undying, and Tanaqui and her siblings are literally the grandchildren of god.
All There in the Manual - The second volume (last two books) is followed by "A Guide to Dalemark," a sort of glossary of terms and characters. It includes supplementary information not defined in the text, as well as juicy tidbits about certain characters' futures.
Almost Dead Guy - In Cart and Cwidder, Moril, without even realizing he's doing it, manages to use the magic of the cwidder to keep his father alive as he's dying.
Badass Normal - Mitt can call on supernatural powers, Moril has a magical cwidder, but Navis...is just extremely competent.
Barbarian Tribe - Played with in The Spellcoats: both warring peoples consider the other group "Heathens", but they're both equally civilized. Lampshaded when they meet and start calling each other Heathens.
This grittling the boys on fayside were at trase with peelers, would you believe! They had sein right too, so it was all kappin and no barlay. We only had mucks. But Biffa was our surnam and you should have seen the hurrel. Now highside is doggers and we have herison from scap to lengday, and everyone looks up to us although we are to be stapled for it. In haste to trethers. Hildrida.
Dawn of an Era - In two separate books: The Spellcoats marks the beginning of Dalemark history, with the crowning of the legendary King Hern, the first king of Dalemark; in The Crown of Dalemark, Dalemark's centuries of interregnum end with the ascension of King Amil the Great.
Downer Ending - The Crown of Dalemark may or may not have one of these depending on whether Maewen is Undying or not.
The Dreaded - Harchad, Earl Hadd's second son. Mitt brushes Harchad's reputation off right up until he sees him...and then everything he's heard catches up with him and he practically wets himself in terror.
Ear Worm - In-universe, Dagner is good at composing these.
End of an Age - Although it's not quite so obvious, Amil's ascension to the throne marks the beginning of an age of reason. Before then, belief in the Undying was pretty much a given, so in Maewen's time, they're mostly considered a superstition.
Fantasy Gun Control - Guns exist in Dalemark, but primarily in the wealthy South, where the earls (who have all the money) can afford to finance gunsmiths and arm their soldiers with guns. In the North guns are much rarer, restricted to a handful of moderately wealthy earls, and smuggled from the South. The North's and South's armor reflects this: soldiers in the South wear metal breastplates with exaggerated curves to deflect bullets.
Immortality - The One has Complete Immortality, while the rest of the Undying seem to be either The Ageless or have a Healing Factor. Kankredin, meanwhile, is physically gone, but his soul continues to poison Dalemark by taking root in the land and feeding off of the chaos it causes.
Incest Is Relative - Pretty much every major character is related, albeit some (much) more distantly than others.
It's For A Book - Maewen's father takes her sudden and intense interest in the reign of Amil the Great to mean that she's writing a historical novel. He's just glad she's doing the research.
Legacy Immortality - When he takes the throne, Mitt takes the name Amil, one of the names of The One. This binds him to The One's duty to root out Kankredin from the land, even after the end of his reign. He passes this name on to his son, as well.
Also, two of Clennen the Singer's children, Brid and Moril, are named after legendary historical figures, Manaliabrid and Osfameron. Their companion Kialan is the Adon, the title given to the heir to the earldom of Hannart. The similarities between some of their experiences (particularly Moril's) and their predecessors' are referenced a lot in Cart and Cwidder.
Literary Agent Hypothesis - A note at the end of The Spellcoats indicates that it's supposed to be a translation of the Spellcoats by historians in Hannart.
Older Than They Look - The Undying, who often look quite young, though they shift between this and looking old.
One Degree of Separation - Moril is directly descended from Osfameron, who is, in turn, a direct grandson of The One. Mitt is directly descended from the last king of Dalemark, who was in turn also directly descended from another of The One's grandsons. Maewen is quite possibly of The One's bloodline, considering her uncanny resemblance to Noreth Onesdaughter. Then there are all the earls and the earls' children and grandchildren.
Maewen is actually descended from both of them. Her father is descended from a line of singers, one of whom was "probably named Clennen," and her mother's line is related to Mitt's.
Our Founder - Not a statue (although there are probably several), but a painting. The mural on ceiling of one of the rooms in the royal palace hilariously depicts King Amil wearing an absurd pair of violet breeches.
Overly Long Name - Clennen is overly fond of these, so his children and his horse all have one.
Pals with Jesus - Mitt, who receives regular visits from Old Ammet and Libby Beer
La Résistance - There are numerous freedom fighting organizations in the South, although they're all pretty much ineffective.
Subverted by Hobin, whose role in the series proper is sympathetic and fatherly. He's biding his time until a proper revolution begins, but the series glossary at the end details what happens to him. After living under the thumb of vindictive Southern earls for his whole life, he refuses to bow to a king, even when that king is his own stepson. He's credited with leading a violent bloodbath in Holand a la The French Revolution, and it's very strongly implied that he murdered his own wife and daughters, who couldn't have been more than five at the time. His epithet is Hobin the Bloody.
Rewriting Reality - Cennoreth the Weaver, one of the Undying, can do this by unpicking and resetting her weaving. She's done it twice. Osfameron's cwidder can also do this, to an extent, by making an idea into the truth.
Rich Bitch - While Hildy's attitude is almost redeemable in Drowned Ammet, who didn't seriously want to slap her for how she treats Mitt in the fourth book?
Simultaneous Arcs - The first book takes place during the first five chapters of the second.
Single Line of Descent - Although there are a number of characters related by virtue of centuries passing during the course of Dalemark's history, Mitt is the only claimant to the throne who is a direct descendent of the Adon.
Sliding Scale of Idealism Versus Cynicism - In the first two books, South Dalemark is horrible and oppressed and North Dalemark is made out to be lovely and free. Then we actually get North in the last book.
Sour Supporter - Earl Keril, Hildy. Possibly other earls and lords of Dalemark were this, since their options during Dalemark's unification were: 1) support it, 2) take a permanent vacation abroad, or 3) dance for the hangman.
Spell My Name with an "S" - In-universe example: spelling and dialect vary between the North and the South, such as with Kialan, whose Southern names are Collen and Halain.
Trilogy Creep - Kind of. The fourth book was published almost fourteen years after the third after Diana's publishers had been begging her for years, but it nicely ties together all three previous books and is quite good. Also, she never would have written it just because her publishers wanted her to if she didn't have an excellent idea of what to write.
Unreliable Narrator - The glossary, of all things. Some of it is straightforward history—meaning it was penned by someone who completely discounts Dalemark's myths.
Verbal Tic - The ultimate evil has one. Kankredin ends a lot of sentences with "eh?"