The King and his wife, Queen Aliza, brought a baby girl into the world; they named her Nadia. However, shortly after Nadia was born, Queen Aliza died due to an illness. After her death, the king had a more strict personality, which Nadia strongly disliked as she disliked being constrained to the castle and wanted to explore the lands. Nadia eventually left the castle without telling anybody to go to the Millennial Fair, using the name "Marle" to hide the fact that she is a princess, at Leene Square, which caused a great stir among the castle.
Disappearance of Nadia
The King became very distressed after the princess left the castle. When she returned with Crono to the castle, the Chancellor told her the castle thought she was abducted and has Crono put on trial for her abduction. Considered innocent by the jury, Crono is sentenced to three days in solitary confinement, but the Chancellor trick the guards into thinking he will be executed in three days, though Crono escapes the jail along with Lucca. Before they leave the castle, soldiers try to prevent them from fleeing until Marle tells them to stop, explaining that the two are her friends and that they should treat them as such. However, the king then enters and tells to her be silent as her duties come before her whims as she is a "Princess before all else". Marle, however, says that she is a person first and a Princess second. The King then says that her "little excursions... outside the castle seem to be having a bad influence" on her. She protests this, saying that "it's common sense" and then says that she "can't live in [the] stupid castle" anymore and leaves, which the King becomes displeased at.
Later in their quest to stop Lavos, Crono's party decide to search for the Rainbow Shell. They find it in the Middle Ages at the Giant's Claw, where it is then brought to Guardia Castle as a royal heirloom. When they travel to the present and visit the castle, the Chancellor tells Marle that she had him worried and mentions that he understands her feelings, that the King "places his realm above all else" and that "it was the same even when... Queen Aliza passed away". Marle questions what he means, and he tells her to forget he spoke, but she insists on learning more, so the Chancellor goes on to say that Queen Aliza's "condition had been frail for some time, but it took a sudden turn for the worse near the end" and "she desperately wanted to see [Marle's] father, just one last time." However, the King refused, saying that he could not leave his work unattended and left Marle, knowing nothing of death, to watch over her mother alone, and she died soon after. He also mentions that "one might well say the King killed" the Queen.
Marle is shocked at this, though the Chancellor tells her not to let it trouble her and asks her to see the King. She searches the castle but can not find him. The party eventually finds the entrance to the courtroom is blocked and forces its way into the courtroom. Inside the courtroom, the King is on trial regarding the existence of the Rainbow Shell. The Chancellor reads an ancestral will that states that the King should have unveiled "the Rainbow Shell to the people at the Millennial Fair, that they might enjoy the blessing of our royal treasure." The King, however, insists that no ancient heirlooms are in the castle. The Chancellor then says that the King is refusing to show the court a glimpse of the Rainbow Shell because he no longer owns it as he sold it for "no reason other than his own greed".
Marle then enters the room, and the King tells her he is being framed. The Chancellor then says that if he is innocent, then he should "confirm the matter with proof". The Chancellor goes on to say that if the King "has not sold the heirloom, it should remain within the castle." He asks Marle to bring the Rainbow Shell before the court, "and his innocence will be beyond question", though he says that he does not expect them to succeed. Marle and the party are then removed from the court.
As the party searches for the basement of the castle for the Rainbow Shell, the court case continues. False witnesses are brought in to testify against the King, with one person saying that the King sold the heirloom to him because "he looked so desperate for the money". Eventually, it is time for a verdict. The result is four votes of guilty to a single of not guilty. The King is then found guilty, and the Chancellor exclaims that the kingdom will be his and demands the King be taken away.
Just before he is taken away, however, Marle bursts into the courtroom and reveals the Rainbow Shard, saying that the Chancellor's scheme for power has failed. However, the Chancellor tells the party that they are the ones who "had better give up" and that if he "can't avenge [his] ancestors the easy way" he will do it the hard way. He then transforms into Yakra XIII and fights the party, though he is defeated and leaves behind an object.
The King tells Marle he is sorry he was so stubborn, though Marle says that she "didn't even think about how [he] must have felt" and that she knows what to say but "the words just won't come out." The King says that it is the same with him and that there was a time when he thought she was lost to him but now when he thinks about it, he realizes that it was him who abandoned her. Marle says that they will talk about everything from now on, saying that she will ask him for advice, tell him about Crono, and ask him about her late mother. At hearing this, he tells her that he is ashamed to admit it, but it has taken him until then to understand her final words, which were, "Someday, when Nadia is older, she'll bring someone she loves to meet you. Welcome the two of them with open arms." Surprised that he heard the Queen's last words, the King explains that she was so young she probably doesn't remember them because she kept saying, "Daddy, I love lots of people! Lots and lots!" This reassured the Queen, seeing her so happy and that she left them with a smile on her face. She asks if she really did call him "daddy", which the King says she did and decides to call him "daddy" from now on. They leave the courtroom and head to the throne room.
At the throne room, the King tells Marle that she has permission to leave the castle, though he expects the utmost caution from her and asks the party to keep her safe. Melchior then enters the castle and wants to make armor using the Rainbow Shell. The party then go back to the courtroom and pick up the object left behind by Yakra XIII, which turns out to be a key. They use the key on a chest in a nearby room and unlock the real Chancellor, who tells them he has to prepare for the Moonlight Parade and runs off.