Lunete's first intervention repays a remembered kindness. When she once visited King Arthur's court, Yvain treated her courteously. Later, after he mortally wounds Esclados the Red at the enchanted fountain and pursues him towards his castle, the falling gates leave him trapped. Lunete recognises him and decides to help. She gives him food and a ring that makes its wearer unseen when the stone is held within the palm. The household searches for its lord's killer without finding the knight whom her practical care and magic protect.

While concealed, Yvain sees Laudine mourning and falls in love. Lunete recognises an opportunity to protect both him and her mistress. The fountain needs a champion, and the man who defeated its previous guardian may be the strongest replacement. Laudine initially rejects this argument, but Lunete continues until she agrees to hear Yvain. His offer of service becomes a marriage supported by the household. During Arthur's later visit, Gawain hears of Lunete's help and places himself at her service, a connection that explains why she will think of him when she is endangered.

Yvain's failure to return by the agreed date undermines Lunete's position. Laudine resents the advice that brought him into her life, and the seneschal, jealous of the handmaid's influence, accuses her of treason. Lunete declares that one champion can defend her against him and his two brothers. The challenge is accepted, and she must produce that knight within the stated time. She searches without success: Yvain is missing, and Gawain is away seeking the abducted Guinevere. She is confined in a chapel as the day of judgement approaches.

Yvain comes upon the chapel after returning to the fountain with his lion. Hearing the imprisoned woman's distress, he questions her and then tells her who he is. Lunete therefore knows his identity before the rescue; she is not kept ignorant by his appearance throughout the episode. He promises to defend her and asks her to conceal his name from others. She fears that fighting three men will kill him as well as herself, but he refuses to abandon the woman who once saved his life.

He returns for the combat, and the lion helps him defeat the accusers. Lunete is cleared, the punishment is turned against those who accused her, and she is restored to favour. Laudine does not recognise her husband beneath the title Knight of the Lion. Afterwards Lunete keeps his secret and helps a later seeker follow his route. Her loyalty now includes both protecting the knight's identity and preparing the ground for reconciliation with her mistress.

At the end, Yvain raises another storm at the fountain. Lunete urges Laudine to seek the Knight of the Lion as a defender, explaining that his own estrangement must first be healed. She obtains an oath upon a relic that Laudine will do what she can to restore his lady's love. Only after the promise is secured does Lunete bring Yvain before her and reveal that the lady is Laudine herself. Her mistress protests, but the promise holds and the couple are reunited. Lunete's narrative comes full circle: the woman who opened the first path to marriage uses speech and a carefully framed obligation to make its renewal possible.