Now Eochy the King had a brother whose name was Ailill Anglounach, or Ailill of the Single Stain, for one dark spot only was on his life, and it is of this that the story now shall tell. One day, when he had come from his own Dun to the yearly Assembly in the great Hall of Tara, he ate not at the banquet but gazed as it were at something afar off, and his wife said to him, “Why dost thou gaze so, Ailill; so do men look who are smitten with love?” Ailill was wroth with himself and turned his eyes away, but he said nothing, for that on which he gazed was the face of Etain.
After that Assembly was over Ailill knew that the torment of love had seized him for his brother’s wife, and he was sorely shamed and wrathful, and the secret strife in his mind between his honour and the fierce and pitiless love that possessed him brought him into a sore sickness. And he went home to his Dun in Tethba and there lay ill for a year. Then Eochy the King went to see him, and came near him and laid his hand on his breast, and Ailill heaved a bitter sigh. Eochy asked, “Why art thou not better of this sickness, how goes it with thee now?” “By my word,” said Ailill, “no better, but worse each day and night.” “What ails thee, then?” asked Eochy. Ailill said, “Verily, I know not.” Then Eochy bade summon his chief physician, who might discover the cause of his brother’s malady, for Ailill was wasting to death.
So Fachtna the chief physician came and he laid his hand upon Ailill, and Ailill sighed. Then Fachtna said, “This is no bodily disease, but either Ailill suffers from the pangs of envy or from the torment of love.” But Ailill was full of shame and he would not tell what ailed him, and Fachtna went away.
After this the time came that Eochy the High King should make a royal progress throughout his realm of Ireland, but Etain he left behind at Tara. Before he departed he charged her saying, “Do thou be gentle and kind to my brother Ailill while he lives, and should he die, let his burial mound be heaped over him, and a pillar stone set up above it, and his name written thereon in letters of Ogham.” Then the King took leave of Ailill and looked to see him again on earth no more.