Achilleus's mother, Thetis, is his main guide and mentor. This doesn't mean that Achilleus listens to her all the time; in fact, she is only too willing to carry out his wishes (such as telling Zeus to help the Trojans) even though she knows it will turn out badly for him. Still, Thetis plays an important role of framing Achilleus's choices for him. Thus, she is the one who reminds him that he is fated to live a long inglorious life if he returns home, but a short, glorious one if he remains at Troy. (Of course, he chooses to remain at Troy and kill Hektor.) Then, at the end of the story, Thetis plays the crucial role of delivering the gods' message that Achilleus must return Hektor's body. This time, Achilleus knows what's good for him and complies.