The Canterbury Tales: The Knight's Tale Part 2, Lines 470-592 Summary
Arcite returns home to Thebes and spends all his time moping and sighing "Allas" – he's that bummed that he'll never see Emily again.
The narrator tells us that he's the saddest creature that ever lived. Arcite refuses to eat, he can't sleep, and he's getting skinny, dried up, and ugly. Plus his skin is turning yellow. Ew. He even bursts into tears when he hears music.
Basically, he's a mess.
After a year like this, Arcite dreams that Mercury (a.k.a. Hermes, messenger of the gods) appears before him and says that if he returns to Athens, his suffering will end. Fate has happy things in store for him.
Arcite decides to heck with Theseus's death threat – he's going back to Athens. As long as he can see Emily again, he doesn't care if his neck ends up on the chopping block.
Checking himself out in the mirror, he realizes that he looks so ugly and so different than he used to that no one in Athens will ever recognize him. Now that's a silver lining.
He dresses up as a poor man and heads off to Athens.
Once he reaches Duke Theseus's court, Arcite looks for work. He's hired by the chamberlain at Emily's house to do odd jobs like hauling water and chopping wood. Despite looking pretty bad, apparently he's still got his strength.
Arcite goes by the name Philostrate and passes a year or two as Emily's page.
Everybody in court loves him. Eventually Theseus promotes Arcite and makes the man his own squire. Basically, he becomes Theseus's right-hand man.