Caedarth

Caedarth is the het ship between Marth and Caeda from the Fire Emblem fandom.

War of Shadows
Marth is the heir to the throne of Archanea, as he was the prince of Altea until he went into exile due to his home city being taken over by his enemies from Dolhr. Caeda is a pegasus rider and was the princess of Talys.

Marth meets Caeda when he went to Talys during his exile to take refuge there. There they spent two years under the care of King Mostyn of Talys, Caeda's father. This allowed Marth to improve his swordsmanship while Caeda trained to become proficient with his spear. When the pirates of Galder descended upon Talys to raid it, called into action by the arrival of Caeda, Marth's forces departed the fort to combat the invasion; upon its fall, on the advice of Mostyn, Marth's retinue left Talys to commence its goal to rebel against the domination of Dolhr.

Caeda was the key to Marth's ability to recruit more soldiers who were willing to join his side through her until finally the army defeats Gharnef and subsequently Marth defeats Medeus thanks to his Falchion.

At the end of the war, spurred by Nyna's urging, Marth finally confessed to Caeda his longtime affections for her, and the two became engaged, which eventually led to the two of them deciding to get married.

War of Heroes
In the year following the end of the War of Shadows, Marth devoted himself to the reconstruction of Altea and had planned a date for his wedding to Caeda, only to be interrupted by a missive from Hardin, now the Emperor of Archanea. Hardin bade Marth to lead the Altean army to Grust to suppress an insurrection there, a command Marth could not disobey owing to Archanea's power over Altea. Leaving Cain in charge of Altea's defense, Marth took Jagen, Arran, Draug, Gordin, and a number of newer knights with him to address the Grustian crisis, leaving Caeda to guard the castle together with Elice, Marth's sister.

However, after defeating several armies of Grust, Macedon and Dolhr, Caeda arrived and broke the news to Marth that Altea had fallen to an assault by the Archanean army, and that only she had escaped while Elice remained behind to hold them off. After that, Marth then decides to defeat first Hardin, then Gharnef and finally Medeus for the second time thanks to his Falchion to put an end to the evil once and for all that could not be done in the War of Shadows.

With the War of Heroes finally over, most of Archanea's noble houses were left in ruins. Almost all of its surviving rulers ceded sovereignty over their territories to Marth himself, and so Marth united the continent as the Archanean Alliance, serving as its first king with Caeda as his queen. Under Marth's reign, the continent experienced a golden era of peace and its wounds began to heal.

As a result of the union between Marth and Caeda, they had descendants who would inhabit Archanea, called Ylisse centuries later. Among the best known descendants of both are Chrom and his daughter Lucina.

Fanon
This is one of the most popular Fire Emblem ships, as Marth is the first protagonist of the franchise and along with Alm and Sigurd, is one of the few that have a closed ending with a canonical partner from his continent, while the other protagonists have an open ending (as the player decides who the protagonist marries with support level A with her) or simply don't get a partner at all.

This couple is one of the best known thanks to the fact that their story takes place in 4 games, three of them remakes. Fire Emblem: The Shadow Dragon and the Blade of the Light for the NES console, Fire Emblem: Mystery of the Emblem for the SNES console, and Fire Emblem: Shadow Dragon for the Nintendo DS console, as well as having an additional story in the Japanese version of Fire Emblem: New Mystery of the Emblem: Heroes of Light and Shadow.

Fandom
FAN FICTION