Ambrosius the Hawk:  The last and only surviving son of Amadeus and Mairead, Ambrosius deftly combines the traits of both his parents, Roman and native.  After the death of his parents at a very early stage in his life, he was raised by his father's farrier Dexter and learned everything about horses from him which did not already come to him naturally.  As Britain begins to splinter without Rome shoring her up, he slips into the gap and begins building a cavalry division under the Council to keep the bickering factions in check.  As time goes on his charisma and farsight take him up through the ranks, making friends and earning enemies, until he stands as a king in his own right with a pack of trained warriors at his back.

Artos the Merlin:  Artos is illegitimate by birth.  At the age of three his mother handed him over to the care of his uncle Ambrosius for safe-keeping, and the boy has been with his uncle ever since.  Like his uncle, he possesses and acute sixth sense, remarkable ambition, and a natural propensity toward warfare on horseback.  Unlike his blood-father, Artos is very keen-minded and respectful, feared or loved by whomever he comes into contact with.  He is nearly inseparable from his uncle.

Artorius: The only child of Mairead and her first husband (also known as Artorius), and Ambrosius' half-brother; father of Artos. 

Kay and Bedwyr:  While two years apart in age, Kay and Bedwyr are practically inseparable.  They grew up in the neighbourhood of Lord Alan's rath, are familiar with the countryside, and exhibit the traits of two colts that were never properly broken in.  However, both are fiercely loyal to Ambrosius and Artos, and Artos is not known to go into a fight without them.

Gaius:  A soldier, a surgeon, and a clergyman, Gaius is one of the more clairvoyant of Artos' Companions.  He joined the ranks of Ambrosius' followers very early in his life and has been neck and neck with the young Merlin ever since.  He is of distinctly Mediterranean origin, and while his life confines him to the Isle of Britain, he is an avid reader in both the Latin and the Greek, not a little in Oscan, and is fluent in many native British dialects.  Since Rufrius' death he has quit the army and manages the cloister below Ambrosius' rath. 

Caleb: As his name suggests, Caleb is Jewish by birth.  Along with Gaius, he joined ranks with Ambrosius and Artos at an early age and, second only to Gaius, is one of Artos' closest friends.  He is of a particularly quiet disposition and musical by nature, but shows a steady hand with horse and sword when the need arises.

The Guttersnipe:  The Guttersnipe is Ambrosius' ward, an orphan of debatably Roman and Icenic extraction.  Having grown up among the Companions it takes some time for her tomboyishness to wear off as she grows older.  About five feet tall with nondescript brown hair and eyes, the Guttersnipe boasts of nothing much save a fiery temper and a firm loyalty to her adoptive family.

Jason:  With no remarkable parentage, Jason is one of those young satellites of Ambrosius' sphere.  He is of an age with the Guttersnipe, and grew up with her and the other boys of Ambrosius' rath.  He exhibits an excellent horse-sense, a frank eye, a cheerful disposition, and a steady hand with a surgeon's tools.

Aithne/Domitia:  Daughter of a Scotti bard and a Visigoth woman, Aithne was captured in a raid and eventually sold across the sea to the Romans, whom she despises.  She finds herself becoming more and more like them, however, which worries her: she clings to what little of her past she has left.  

Gwenhywfar:  Gwenhywfar is one of Vortigern's daughters, and a perpetual thorn in his side.  As a bard, and a very intelligent as well a beautiful young woman after the Celtic strain, she taunts him with her songs of Ambrosius' and Artos' exploits throughout Britain.  She plans one day to join them and quit her father's hall forever, but even with Ambrosius and Artos abroad the land is still too unsafe for a woman to travel alone; and so she stays at home, plotting and scheming.

Master Lucius: Master Lucius is a Greek, an historian, a horse-trader, and excessively shrewd as well as remarkably kind.  He is one of Gwenhywfar's few friends among her father's people. He is a sickly constitution and often ill, so that he confines himself mostly to reading and studying, and observing that amphibious creature, the human. 

Vortimer the Fox:  Typically known only as "the Fox," Vortimer, like his sister Gwenhywfar, does not share his father's dislike and distrust of Ambrosius.  Something of a mercenary, he often helps Ambrosius and Artos when they need him, and on his own cleans up petty squabbles and errant raiding parties that fall under his eye.  He is friendly enough, with a disposition not unlike Kay's, but like Ambrosius himself he has a strongly native strain in him and is not always the most stable of characters. 

Vortigern: A king in Britain, loathing all things Roman in general, and hating Ambrosius in particular; he was a member of the Council of Britain.  As the balance of power began to shift and Ambrosius began to supersede the Council, Vortigern sought to put a stop to the Hawk's flight.  Unfortunately for the king Britain needed Ambrosius too badly and the two fell out for good.  Vortigern's power-base collapsed to almost nothing and he lives in mortal fear of his younger rival.  His four children are Vortimer, Gwenhywfar, Catigern, and Pascent.

Mordred:  Young Mordred's situation, not unlike Jason's, is one of being an orphan and a satellite of Vortigern's rath.  His parentage is completely unknown, though it is believed with credit that he hails from the Old People.  He exhibits their smallness and their darkness, their skill in witchcraft, and their long grudge against their overlords.  He loves no one, and takes great delight in hating, in pain, and in killing.

Calidus: For a while Calidus lived alongside Jason and the Guttersnipe in Ambrosius' rath, but around the age of twelve was dismissed on moral grounds.  He washes up alongside Mordred in time, supposing to find something of a friend in the little dark boy, little realizing he is nothing more than a kind of pawn.

Rufrius:  The previous clergyman in Ambrosius' cloister, Calidus' lover.  He is deceased.

Hengist: "The Stallion;" Hengist was invited to Britain by Vortigern to put down the uprisings of the Picts.  He eventually becomes king of the area of Kent, and looks to strengthen his hold on the Island.

Horsa: "The Horse;" Hengist's brother.

Lord Alan:  The next-door neighbour to Ambrosius, a member of the Council.

Murgen:  Lord Alan's wife, a woman of the Old strain.

Servilla: Vortigern's wife, a daughter of the general Magnus Maximus (who is deceased and doesn't have any bearing on this story, poor chap).

Rowena: Hengist's daughter, a witch.

Iceni:  A native horse-breeding tribe from the Norwich area; most famous for its character Boudicca.

Brigantes: "The Blue Shield People;" a large native tribe from northern England.

Picts: A loose term for the tribes of Scotland's territory.

Also, if any of you feel like figuring out which of the shades of Hades Master Lucius is quoting from at any given time, best of luck with that.