Cligès begins with the story of his parents, Alexander and Soredamors. Alexander, the son of the Greek emperor (also called Alexander), travels to Britain to become a knight in King Arthur's realm. While at court, Alexander gains favor with King Arthur, is knighted, and assists in retaking Windsor Castle when it is taken by the traitor, Count Angrès. During his time at court, Alexander meets Arthur's niece, Soredamors and falls in love but is unable to express his feelings to her. She feels the same, but neither party is able to tell the other how they feel. Queen Guinevere takes notice and encourages them to express their mutual love. They immediately marry and a child is born. This child is Cligès. Alexander and his family then return to Greece and find out that Alexander's brother, Alis, has claimed the throne to Greece since their father has died. Although Alexander is the rightful heir to the throne, he concedes to Alis with the condition that Alis will not marry or have children so that the throne will pass to Cligès. Alexander dies and Cligès is raised in Greece. Many years after Alexander's death, Alis is persuaded to marry and he chooses the daughter of the German Emperor, Fenice. Thus begins the story of Cligès and Fenice. Cligès falls in love with his uncle Alis' wife. She also loves Cligès but he follows in his father's footsteps to Arthur's kingdom to be knighted. Like his father, he does well in King Arthur's court, participating in tournaments and displaying courtly manners. He is knighted and returns home. Cligès and Fenice still love each other and Fenice concocts a plan to use magic to trick Alis to escape. Using the magic of her governess, she fakes her death so that she and Cligès can runaway together. They succeed and hide in a tower but are found by Bertrand, who tells Alis; Cligès goes to Arthur to ask for help in getting his kingdom back from his uncle, but Alis dies while he is away. Cligès and Fenice are free to marry and Cligès is now emperor.

Question: How does Cliges become emperor and free to marry Fenice?
Answer: When Alis dies Celiges is able to take the thrown and marry. 
Alternative answer: Alis dies