Son of Alexander and Tantalis, thus the younger brother of Arthur's Greek knight Alexander. Alis was crowned Emperor of Greece and Constantinople when their father died and the ship sent to Britain sank on the way, leaving a single survivor who, preferring the younger brother, brought back a false account of the elder's death. At first reluctant to believe Alexander was still alive when Acorionde came from their ship to tell him so, Alis decided on the advice of his counselors to avoid another Polyneices and Eteocles situation by cobbling up a compromise which gave the true power to Alexander while Alis retained the name of emperor in return for a promise never to marry and thus ensure the eventual passage of the crown to Alexander's son Cligés.
This promise Alis, who seems never to have shown much strength of personality, finally broke after Alexander's death, when his nobles pestered him to marry. They had already picked out the emperor of Germany's daughter Fenice for his bride. Cligés helped his uncle keep Fenice from her former fiancé the Duke of Saxony, but the princess, having fallen in love with Cligés, enlisted her nurse Thessala to cheat Alis by means of a potion that made him dream about having relations with her and mistake his dreams for fact, while the marraige remained unconsummated.
When Cligés returned to Constantinople after spending about a year in Britain, Alis made over to him everything except the crown and the empress. Cligés reciprocated by helping himself to the only-to-eager empress, stealing her away (the scheme being her own) to live secretly with her in a marvelous tower built to order by Cligés serf John, while Alis and the rest of the empire supposed her dead of disease. Discovered by one Bertrand, Cligés and Fenice escaped to Britain, where he enlisted his great-uncle Arthur to war against his other uncle Alis; but before it could happen Alis died of grief-included madness. After the death of Alis, Cligés and Fenice returned to Constantinople, where Cligés ruled as Emperor.
Alis is a form of Alexius, a name, or title, borne by a number of Byzantine emperors.