Eiryon

Eiryon is the het ship between Eirika and Lyon from the Fire Emblem fandom.

Fire Emblem: The Sacred Stones
In the past, Lyon - prince of the Grado Empire - was great friends with Eirika and her twin brother Ephraim, who were the princess and prince of Grado's neighbor Renais. The three supported each other, Eirika particularly supported Lyon's research into the usage of Grado's Sacred Stones to help the world despite the inherent danger of it. Years later, Lyon - under the influence of the demon king Fomortiis - sets into motion Grado's invasion of Renais, one that sets Eirika and Ephraim into a quest to find the other Sacred Stones. During the quest, Eirika wonders to Ephraim how Lyon is doing and why he would let his father do what he did. Shortly afterward, the siblings would separate for a bit before reconvening and continuing the search together

The search leads them to a village within Rausten, where they're met by a returned Lyon. Before Eirika can welcome Lyon back, Ephraim reveals to her what Lyon him earlier about starting the war, which Eirika flatly refuses to believe. Before Lyon can attempt to defend himself from the accusations, Fomortiis asserts his control to destroy their gathered Stones, kill Ephraim, and take Eirika as Lyon's own. The two fight in the ensuing battle, with Eirika pleading with Lyon to stop fighting while Fomortiis uses his romantic attraction to Eirika against her. Lyon is ultimately defeated and is forced to retreat, with Eirika and Ephraim's army in pursuit.

While pursuing Lyon, Eirika is informed that Fomortiis' control is so great that not even the Sacred Stones can restore him. However, she has confidence that Lyon can ultimately be saved. The pursuit leads Eirika to finding a weakened Lyon in a cavern asking for the Sacred Stone in her possession so he can sever his connection to Fomortiis. Eirika gladly hands the Stone over, only for Fomortiis to reveal he was acting to bring her to him before destroying the stone and retreating once Ephraim arrives. Eirika is devastated about what just happened, knowing that the Lyon she knew really is gone.

Eirika and Lyon reunite in the Black Temple while the latter is beginning the ritual to fully revive Fomortiis. Briefly breaking free of the Demon King's control, Lyon apologizes to Eirika for his weakness and that everything was his fault and telling her to kill him before Fomortiis can be revived. Eirika ultimately complies with Lyon's final request and kills him in the ensuing battle, saying that the Demon King won't desiccate his body anymore. As Lyon dies free of Fomortiis' control, he tells Eirika that he's glad she stopped him and finally tells her that he loved her.

With the war over, Eirika vows to fulfill Lyon's dream of bettering the world.

Fire Emblem Heroes
Eirika and Lyon are two of the heroes that the player can summon separately via the Breidablik to help Alfonse and his sister Sharena defending their kingdom Askr from the Emblian Empire. Unlike in their original game, Eirika and Lyon can develop a bond via support. They can raise their level of support in the following ranks: C, B, A and S if they stand together in gameplay. Each of them have variants besides their base forms: Eirika has six variations while Lyon has three by himself and one as the partner of Ephraim.

Eirika and Lyon both received younger childhood variants in the "Childhood Encounter" focus in April 2021. In the associated paralogue, the two of them were brought from a point when they didn't know each other by the goddess Thórr for a trial. While wandering around the forest they were brought to, Eirika - along with Ephraim - ambush Lyon when they think he's trying to attack them. Unaware of who he is at this point, Eirika asks Lyon if he was brought against his will just as she was, to which he confirms but the three have to retreat when Ephraim notes someone approaching, regrouping with the younger versions of others the three would know in their future. The group eventually reach the edge of the forest, where Thórr sends them back to their time without the memories of what had transpired but keeping the feeling of connection made between them, including Eirika's and Lyon's.

The two would then receive summer variants in the "Taken by the Tide" focus in late Summer 2022. In the associated paralogue, the two of them - as well as Seth - went to the beach for a vacation. When Seth notes the potential dangers of the beach to Eirika, Lyon laments that he might not have prepared enough considering they were her protection, though Eirika waves off the concern before pushing Lyon into taking a swim. After Lyon notes how far Eirika had swam away from them, Seth attempts to catch up and leaves the Grado prince to wonder if he could be doing more for her considering Seth has her protection handled. Eirika eventually returns to Lyon, where he shows that - while Seth was getting her back - he made a sandcastle version of Renais Castle - complete with seashells to represent her, Ephraim, and Seth. Eirika, however, adds her own seashell to represent Lyon (placing it between "her" and "Ephraim") to which the prince now believes completes it. A tide ends up destroying the sandcastle, but while it saddens Eirika to see his work gone, Lyon is happy she got to see it at all. This brightens Eirika as she says she won't forget the memory, even saying Ephraim would be jealous of Lyon when he learns about his sandcastle making skills.

In addition, Eirika and Lyon also stared together in a Bound Hero Battle. Before the battle, Eirika - in a variant that utilizes tomes - begins to claim to do something with the magic Lyon taught her, but stops when she notices him struggling. Lyon - in a variant possessed by Fomortiis - tries to make Eirika go away before he can hurt her.

Fanon
Eiryon is a smaller ship within the general Fire Emblem fandom, but is supported proportionally more within the fandom for Sacred Stones. Eirika's and Lyon's story is seen by fans of the ship as a tragic tale of unrequited love. It's not as popular of a ship as Lyon with Eirika's brother, but still well liked.

On AO3, Eiryon is a less written ship for Fire Emblem, with tagged entries currently in the 50's. It's the second most written ship for both Eirika and Lyon, behind Eirichel and Ephlyon, respectively.

Fandom
FAN FICTION