Kallura

Kallura is the het ship between Keith and Allura from the Voltron: Legendary Defender fandom.

Season 1
When Keith discovers the Blue Lion along with fellow Garrison cadets and the formerly missing pilot Shiro, the Blue Lion activates and flies the group to Arus where they awaken Allura. She guides Keith and the other new Paladins of Voltron into locating the missing Lions and fighting against the evil Galra Empire.

Later, during the battle to retake the Castle of Lions from Sendak, Allura and Keith coordinate a strategy to defeat him, with Allura accessing the Castleship's computer systems while Keith battles the Galra Commander, effectively distracting Sendak until the princess can lock him in a barrier generated by the computer - a plan the two execute near wordlessly.

After Allura uses her energy to heal an entire planet, the Paladins go on a training mission while she rests. When it turns out the mission will take longer than planned, the Paladins contact her and Lance, Keith's teammate, flirts with the princess to the point of angering her and exasperating the rest of the team with his antics. Keith, recognizing Allura's feelings and Lance's lack of focus, orders Lance to stop. Lance believes this means Keith is jealous that he is not the object of Allura's affections; this is simply Lance's delusion, as there is no indication of any romantic interest between Keith and Allura nor from Allura towards Lance, and she was insulted by Lance's objectifying and belittlement of her. Later, Keith reminds the team of Allura's weakened state, saying the struggle of their current mission pales in comparison to the princess' strained health.

As the team tries to gather information on the Galra Empire, a mission goes awry and Allura sacrifices herself to allow Shiro to avoid capture. She becomes imprisoned in the Galra Empire's headquarters. The Paladins wish to rescue her, but Keith suggests they best not make the attempt, as bringing Voltron directly to Emperor Zarkon seems like a terrible idea. He admits he is not fond of abandoning a teammate, but is thinking like a Paladin. The team attempts a rescue anyway and Keith fearlessly battles Zarkon to protect his team, give them a chance to save Allura, and possibly end the war. It turns out Keith's suggestion was entirely warranted - Allura herself is dismayed that the Paladins have brought the Lions to Zarkon, as he was the original Paladin of the Black Lion and Voltron's power must not fall into his hands.

The rescue is successful, but the team barely escapes and becomes scattered by a corrupted wormhole.

Season 2
In "The Ark of Taujeer," Keith and Allura both fear Zarkon keeps finding the team through them. Late at night, they both run into each other while making their escape. Keith tells Allura to not try to stop him, in response, Allura says she won't, but that she's going with him. Together they leave. Later in the morning, when the others can't find them, Coran realizes one of the pods was launched. Shiro tells him to connect that pod. Shiro tells them to come back to the ship immediately, but Keith and Allura must know if they're what keeps Zarkon finding them, so they stay.

Hours later, Coran calls them, saying Zarkon isn't following either of them as a Galran fleet is where the rest of the team are. Keith activates the booster Pidge put on the pod, but the pod explodes, ejecting Keith and Allura into deep space. They go in different directions, Keith uses his jet pack and flies to Allura, telling her to grab his hand. She does and they twirl for a moment, holding each other close. Keith asks Allura if she's okay, when she says she "believes so" she asks him if his radio is still working. They get no response, so they begin their slow journey back to the team. Sometime later, the Red Lion finds Keith and there for Allura as well. Together they ride to where the others are battling. Once back on the castleship, they apologize for leaving.

In "The Belly of the Weblum," since the the reveal of Keith's Galran heritage, Allura begins giving him the cold shoulder. Keith is hurt by this, after a hug with Shiro, Keith turns to look at Allura and sees her cold expression. Keith visibly looks heartbroken at this. Later with Hunk in the Yellow Lion, Hunk begins asking questions about the Blade of Marmora, Keith snaps, saying, "It's bad enough that Allura hates me now, but can you just lay off?"

In "Best Laid Plans," Allura is still giving Keith the could shoulder. Early on in the episode, Allura merely glares at Keith. It's when Keith says he's going to infuriate Zarkon's base, that's when Allura makes the effort to speak with him. As Pidge is helping Keith prepare his mission, Allura comes in asking Pidge if she can speak with Keith alone. Once Pidge is gone, Keith asks if there's something he can help her with. Allura goes on to say how the Galra have done terrible things, from destroying civilizations, to taking her family. Over time she has come to consider Keith (and the rest of the paladins) as her family. She continues to say how she wanted to hate him, but how the problem was her the entire time, how her anger blinded her. She runs into Keith, Keith is stunned, but slowly raises his hands to hug her back. Allura apologizes for misjudging him and pleased for Keith to come back to them, he says he will.

Season 3
In "Hole in the Sky," Team Voltron gets a distress signal from an Altean ship. Allura is adamant they check it out. They cross through to an alternate reality, after searching for an beings in distress, two figures drop down from a ceiling hatch. Everyone is shocked when it's Shiro's face they're seeing. After a brief battle, other Alteans board the ship and the the Shiro look-alike and company leave.

Sometime later, Keith and Allura are speaking with Hira, the leader of the other Alteans; Allura is delighted in knowing of peace movements through out their galaxy. Hira then tells them of how they keep people in check; by controlling them. Keith is quick to quip back how they're taking away their free will, to which Allura looks at him is shocked. Allura is soon overwhelmed by the thought of returning to Altea, to which Keith tells her that "this might not be the Altea you remember" and that "it wasn't that long ago we thought all Galra were bad." Allura tells him that "these are her people." She then powers up the ship, releasing the comet/ore from it's hold.

Shorty after, Lance, Hunk, Pidge, the Shiro-look alike (Sven) along with his partner (Slav) are captured by the Alteans and are taken to where Keith and Allura are. Keith yells at them to let their friends go. At the mention of "slaves" from Slav, Allura is bewildered, looking to Hira. A battle breaks out and they make it back to their own reality, with Lotor taking the comet/ore once they're back.

Allura sits alone overlooking the galaxy. Keith walks up to her, telling she did the right thing. Allura is sadden to mention how Lotor managed to get the comet/ore. Keith tries to comfort her, but is unable to do so, as the Galra will have a weapon as "powerful as Voltron."

Season 4
In "Code of Honor," Allura greets Keith when he comes back from his mission with the Blades of Marmora. At first Keith believes she's going to give him lecture, which he "isn't in the mood for." Allura says she knows what happened on the mission, to which Keith whispers, "Thanks." Though when Allura does start speaking, she soon divulges into a lecture-like talk, which Keith doesn't want any of. Allura continues by saying how the Blade of Marmora can go on without Keith, while Voltron cannot.

Season 1
Return of the Gladiator
 * Allura goes to greet an unknown creature. Keith, not taking any chances, moves to shield Allura when the creature gets too close.
 * Keith is seen smiling at Allura while he watches her interact with the local Arusians.

Fall of the Castle of Lions
 * As the Arusian village is being destroyed, Keith goes down to get a closer look. Allura yells Keith's name as he descends into the flames.

Season 4
Code of Honor The Voltron Show!
 * Allura and Keith make eye contact while the other paladins work.
 * Allura plays Keith during the shows.

Fanon
While nowhere near as popular as Klance and Sheith, the pairing maintains support from a vibrant fanbase. On AO3, it is the second most written ship for Allura.

Fandom
AO3

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Trivia

 * The ship is traditionally the canon "flagship" of the Voltron franchise. Legendary Defender is the first incarnation of the characters Keith and Allura that have yet to be in an established relationship or show any romantic interest in each other.
 * Previous Voltron media traditionally had Lotor obsessively in love with Allura and fighting Keith to capture her. This is also not present in Legendary Defender.

Variations

 * Hallureith refers to the ship between Hunk, Keith and Allura
 * Kallurance refers to the ship between Lance, Keith and Allura
 * Keirotora refers to the ship between Lotor, Shiro, Keith and Allura
 * Shallureith refers to the ship between Shiro, Keith and Allura