Rune meets Chaz
and Alys early in the game when they discover the ruins of the Motavian village of Molcum. From the moment you meet him it is evident that there is a connection between him and Alys that is most likely romantic but is never directly explained. He'll immediately accompony you on your journey to the town of Tonoe. At this point Rune is likely several levels higher than the rest of the characters in your group, making it much easier to progress through the cave and thus continue the story.
At the town of Tonoe Rune will leave the party, only to reappear later in the game while searching for the Psycho Wand, a powerful relic that will allow you to fight Zio, the evil wizard and cult leader resposible for many of the problems in the first act of the game. From this point onward Rune will fight at your side as the group's resident magician.
Later in the game, when visiting the Esper mansion on Delzolis, you are taken to meet Lutz, one of the characters from the original Phantasy Star
. Lutz has supposedly been sleeping for thousands of years in a magic slumber until he is needed to guide the Espers in a time of crisis. Instead you find a dormant telepathy ball. You find that Rune is much more than meets the eye. In fact he is current caretaker of Lutz' memories and has been tasked to once again choose a hero for the Algo System
; unsurprisingly his choice is Chaz.
Rune is a central character to the Phantasy Star IV storyline and indeed the overall canon of the Phantasy Star franchise. His memories are one of many links between the final episodes and the previous games in the series, making him perhaps the most important ally to Chaz in his goal to save the system.