Arielsa

ArieIsa is the femslash ship between Ariel and Elsa from the Frozen, The Little Mermaid and  Once Upon A Time fandoms.

Canon
As Ariel and Elsa are from different series, they have never met. However, the two do appear in Ralph Breaks the Internet, and have a few brief interactions. Ariel joins Elsa on Jasmine's carpet, after emerging from the water spiral. Elsa then freezes the water spiral, and Ariel will stand in front of Elsa when they reach Ralph. In Once Upon A Time, Elsa end up unknowingly traps Ariel in a bottle along with Blackbeard's crew.

Ariel and Elsa both lost their mothers to ship wrecks. They also both have castles that are situated by the sea, and have a second castle in a completely different environment. The two were both able to bring two different types of people together, but end up having to leave their families in order to start anew in the other land.

Fanon
Elsa and Ariel are shipped by a few fans, therefore is considered a rare pair. Artists and writers who enjoy Modern AU's depict the two in the clothes they wore in Ralph Breaks the Internet. The ship became more popular after the Frozen II trailer, where Elsa is shown running across the ocean, and fans depicted Ariel coming upon Elsa as she attempts to cross.

A few fanfics have Ariel meeting Elsa as either a mermaid or a human. Since Elsa's home castle sits next to the ocean and Ariel is fascinated by the surface world could lead to the mermaid coming across Elsa. This is often portrayed in fanfictions. The most common scenario usually involves Ariel saving Elsa from drowning. Elsa usually is the captain or is aboard a ship, which also ties to the popular theory that Frozen and The Little Mermaid take place in the same universe. Most of the Human!Ariel fics of Arielsa circle around modern AUs, as Elsa and Ariel meet and befriend one another in high school. Because of the secrets they keep from the people around them, fans see Elsa and Ariel bonding from the struggle that comes from it and how they could overcome it, despite their fears.

On AO3, the ship has over 10 works. While fanfiction.net has 12 in its Little Mermaid/Frozen category, with only 3 placed under pairing.

Fandom
FAN FICTION
 * Ariel/Elsa (Disney) tag on FanFiction.Net
 * Ariel/Elsa (Disney) tag on FanFiction.Net

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Trivia

 * The group photo taken with Vanellope, in the trailer for Ralph Breaks the Internet, Elsa is seen above Ariel.
 * The two are from two of the few Disney films that have become Broadway shows. As well as them being featured in the Disney on Ice show.
 * They are two of the limit time characters, with their own limit time clothing, in Disney Magic Kingdoms.
 * They are two of the Disney Princess characters who met Sora in their own home worlds in the Kingdom Hearts series, as well as both of them appearing in the same game, Kingdom Hearts III.
 * Elsa is the oldest sister while Ariel is the youngest.
 * They each have two castles.