Summons opens when two school-age wizards summon half-elf kama Rhysel from her home world, Barashi. This would normally be mostly harmless... except that no one can undo the spell, which means Rhysel is stuck on Elcenia until someone can. Rhysel adjusts to the new planet itself fairly well, but finds herself both experiencing and creating various upheavals, ranging from the personal to the romantic to the magical.
On the bright side, she does suddenly have a lot of time for her research.
Blood is the story of Talyn, who was a secondary character in Summons. He can read minds, and does. The story starts with him breaking his arm cliff-diving, chronologically a little after the beginning of Summons. Talyn is very interested in how things work; for example, he chose to leave his arm broken longer so that he could see the healing done slowly and learn more about the process.
Silver is the story of Ehail, who was a tertiary character in Summons. She is a silver shren and the wizard of her house. The story starts at the very end of Summons. Ehail starts dating Gyre, Rhysel's brother. and eventually marries him
Empaths is the story of Ilen, another tertiary character in Summons, a jade shren that takes care of babies and suffers panic attacks over even the mention of the outside world. He is the brother of Narax and Keo.
Siaddaki is the story of Mallyn, an abused teenager who comes to Elcenia to seek help.
Red is the story of Finnah, a shren who lives in the Kep Island Shren House until she moves to Binaaralav Academy to learn kamai.
Blessed with Suck: Hearers, vampires that hear objects talking about themselves. Every object, all the time. And they can't turn it off. Vampiric Inanimate Audition is considered a mental illness because it eventually does make the vampires crazy.
Bittersweet Ending. Not to all novels, only with Empaths, it ends with Ilen and Hallai breaking up due to her using empathy to manipulate him, Ilen is left alone and still unsure how to take care of himself, but he at least has family and friends now
The Dark Arts: A subset of kamai is called the "forbidden workings" and includes transferring lifespan from one person to another. This is implied to be one of the least nasty parts of the forbidden workings; the forbidding came after a worldwide war against the abuse of power by kyma.
Rhysel is an elemental kama, which means she can manipulate all four elements.
Mages on Elcenia get power over one such element after "dying" by that element: for instance, a water-type would drown, but be alive at the end.
Fantastic Racism: Elcenia seems mostly free of this, with the notable exception of anti-shren sentiment from dragons. Biologically, shrens seem to be the same species as dragons, but dragons and shrens agree that shrens are not dragons. In Barashi, magic is viewed with suspicion.
Hearers, who are considered insane, despite actually having the power to hear objects; see Blessed with Suck.
Barashin Dragons are far less kind to humanoids than the Elcenia couterpart.
Flat World: Elcenia is one; planets there are naturally regular polygons (though the moon is round, gray, and dusty...)
Functional Magic: Several kinds. Barashi has kamai, which is Force Magic fueled by mana, and the gods will sometimes intervene if requested and paid. Elcenia has several, of which the most prominent in the story so far is wizardry, a form of Rule Magic or Ritual Magic that mostly behaves like engineering, and witchcraft, which is alchemy.
Healing Hands: Lights have the ability to heal anything from grievous wounds to minor headaches with a light they form by cupping their hands, but they cannot heal themselves or other lights. Lights find sunlight to be very pleasing, even nutritious.
Homosexual Reproduction: Directly stated to be possible via magic, though male couples require a surrogate, and female couples can only have daughters.
I'm Having Soul Pains: In Elcenian dragons not flying causes a longing called esu. After a while esu will manifest as physical pain and steadily grow worse without upper limit. The only way to end esu is flying under their own power.
Shrens are dragons who can't fly with their natural wings and therefore suffer from esu. They eventually stop caring about most pain as irrelevant; a shren who broke most of her bones wasn't particularly bothered by it.
Immortality Begins at Twenty: Not actual immortality, but Elcenian dragons' human forms age ten times slower than actual humans (with the equivalent age for other races), and stops at equivalent age 20. Barashin elves and Barashin halfbloods all stop aging at 25 and stay in that age for a few centuries, then start aging again. Vampires are a straight example of this trope.
Interspecies Romance: There hardly seems to be any intra-species romance. As of Chapter 12 of Summons, all romantic involvement has been between people of at least partially different species.
As of Chapter 13 of Silver only three of the twelve most prominent couples that appeared so far are the same species through and through, with three other couples involving a partial species match with a mixed species partner.
Word of God is that this is because the writing focuses on interactions between Elcenia and Barashi.
Empath, the fourth book, is the first one to have a protagonist couple of the same species and planet.
This is part of the Draconic "culture": before marrying a dragon mate for life, they have several marriages with humanoid species.
Our Elves Are Better: Elcenian elves age like humans, only three times slower, while Barashin elves age like humans until they reach adulthood, then stop aging entirely for a millennium or so.
Our Gods Are Greater: Barashi has a singular set of 24 gods with physical forms (which they disguise to resemble whoever is looking at them) and omnipotence in matters of their own world. Their existence is a universally known fact. Elcenia has a number of mutually contradictory religions and no gods stepping forward to settle the issue.
Our Vampires Are Different: Elcenia's vampires aren't undead in the sense of being created from other creatures, but rather a race that reproduces on its own like any other. They can shapeshift between bats and pale humanoids, and need to drink blood for sustenance. Their life spans depend on the lifespan of the creature whose blood they drink.
Ship Sinking: Invoked by Samia, because she doesn't like the idea of Narax getting together with anyone she knows.
Standard Time Units: Played straight within each world, and averted between them. The day-night cycles of the two worlds have different lengths, among other things.
They Call Me Mister Tibbs: Aar Kithen repeatedly declines Rhysel's offer of changing to First Name Basis and keeps calling her Aaral Camlenn. Once they start dating he agrees to call her Rhysel and be called Tekaal in private.
Translator Microbes: In the form of a natural dragon ability and various wizard spells and kamai.