Saga of the Exiles

Julian May's Saga of the Exiles tells the story of human malcontents who leave the Galactic Milieu, a Federation of six allied psychic races including Humanity, and travel via a Portal to the Past to the Pliocene Era of Earth's history 6,000,000 years ago. The past is not quite what anyone expected.

The time-travelers arrive to discover the Pliocene is already inhabited by a dimorphic race of aliens ('exotics'). The exotics, who have fled their home galaxy because of religious persecution, are marooned on Pliocene Earth as well. The exotics have difficulty reproducing on Earth, and so have enslaved many of the humans in an effort to overcome this problem, interbreeding with the more robust humans and influencing the legends of Celtic Mythology and The Fair Folk.

The books making up the tetralogy are;

• The Many-Colored Land
• The Golden Torc
• The Nonborn King
• The Adversary

Tropes used in Saga of the Exiles include:

• Ascend to a Higher Plane of Existence - Marc and Elizabeth. Although Marc comes back as Atoning Unifex in the Galactic Milieu trilogy, and it is revealed that Elizabeth died.
• Bread, Eggs, Milk, Squick - Felice's dagger is useful for "picking teeth, cutting sandwiches, pricking out transponders from rustled cattle, and putting out the lights of casual assaulters."
• Brought Down to Normal - Elizabeth after her accident in the Milieu. Her power is then restored by the trauma of passing through the time-gate.
• Butt Monkey - Tony Wayland, oh so much. This guy just can't catch a break Until the very end. Of course, this is to be expected given that he is a not so subtle nod to the mythical Wayland Smith.
• The Fair Folk - The Tanu and Firvulag, who match well to the Seelie and Unseelie Courts respectively, the Tanu representing the tall and beautiful archetype, while the Firvulag the darker, more goblin-like side. Most of the named exotics correspond directly to members of the Tuatha de Danaan and the Fir Bolg or Fomor -- Nodonn/Nuada, Lugonn/Lugh, Pallol/Balor, et cetera.
• Fantasy Gun Control - the types of weaponry permitted through into Exile are strictly controlled, and the Tanu confiscate it all anyway. The Tanu and Firvulag don't use firearms, except for some of their ritual weapons.
• Grey and Gray Morality - So, who are the good guys?
• Half-Human Hybrid - Justified by the sentient ship having been told to find the most compatible planet for the exotics' exile.
• Honor Before Reason - the exotics fled to Earth so they could continue to practice their bloody apocalyptic battle-religion, rather than live in peace as part of the emerging Duat Mind.
• Horse of a Different Color - Humans who serve the Tanu train chalicotheriums ("chalikos"), a Pliocene-era herbivore, to fill the role of horses.
• I'm a Humanitarian - The larger Firvulag (Ogres) are often this. From their point of view, this is hardly immoral since they consider humans to be nonpersons.
• No Man of Woman Born - The Nonborn King.
• Older Than They Look - Many of the the Ocala rebels have undergone rejuvenation, so they look thirty or forty but are really a few decades older. Owen Blanchard, the oldest of the Rebels, is about a hundred and forty and looks to be a normal old man. Marc is also self-rejuvenating; he looks fairly young but is actually about seventy at the time of the series.
• Psychic Powers - The Tanu are organised into five psychic guilds: each guild has a guild leader and its own heraldic colours, which allow others to instantly recognise the person's primary metapsychic power. Coercive (Blue), Creative (Green), Psychokinetic (Rose-gold), Farsensing (Purple) and Redactive (Red).
• Psycho Lesbian - Felice
• Really Seven Hundred Years Old - The Tanu and the Firvulag, many of whom came to Earth on Brede's Ship, making them at least about a thousand. And then there's Brede herself.
• San Dimas Time: The time-gate always drops people six million years before the current modern date, so effectively the same amount of time has passed on both sides since travel began.
• Satan - Marc is identified as The Adversary.
• Science Fantasy - Spaceships, psychics, Portal to the Past and The Fair Folk. Something for everyone.
• Shapeshifting - Many characters are able to shapeshift through use of the Creative Metafunction. Aiken Drum turns into a series of different animals reflecting his personal growth and increased metapsychic strength. Marc turns his son Hagen into a fish for a while as a punishment and In the later books Felice can turn into a raven. Also see Voluntary Shapeshifting below.
• Stable Time Loop - Marc Remillard and Elizabeth Orme travel to the Duat galaxy to help them with their psychic development. Afterwards Marc returns alone to the Milky Way and attempts to raise the native species to operant metafunction. His first success is with the Lylmik, who are the ones who create the Galactic Milieu, who in turn create the time-gate that allows Marc and Elizabeth to go back to the Pliocene in the first place...
• Too Kinky to Torture - Felice, eventually. Or rather, torture drives her insane to the point where pain becomes no longer a bad thing. And also unlocks her massive psionic super-powers, allowing her to destroy the people who were torturing her. Oops.
• Trickster Archetype - Aiken Drum
• Twin Telepathy - Kuhal Earthshaker and Fian Skybreaker are Tanu twins who appear to share one mind through telepathy. When Fian dies, Kuhal has to learn to be a whole person.
• Vagina Dentata - The Firvulag
• Voluntary Shapeshifting - The Firvulag appear to do this, though it's accomplished through illusion rather than actual bodily change, and other Firvulag can see through it.
• Weaksauce Weakness - Iron is deadly poisonous to full-blooded Tanu and Firvulag.
• The Wild Hunt - carried out by levitating Tanu knights in glass armor.
• Woobie, Destroyer of Worlds - Felice, although YMMV somewhat on how much of a woobie she is. But for a certainty, bad things happened to her and tipped her into raving insanity (and power).