Lumither

"Yes, of course. "Home" is wherever we are together."

- Archon Quest: Chapter 1 - Act 4: We Will be Reunited

Lumither is the family ship between Aether and Lumine from the Genshin Impact fandom.

Canon
At the beginning of the game, Aether and Lumine were separated by an unknown god. When the Traveler then wakes up in Teyvat, they immediately begin searching for their respective sibling. They've had little canon interaction since.

Archon Quests
In the Prologue of the game "The Outlander Who Caught the Wind", The Knights of Favionus asked the Traveler what reward they wanted for defeating Dvalin and saving Mondstadt, to which the Traveler replied that they wanted Missing Person Posters put up around Mondstadt to look for their lost kin.

Later, Chapter I of the game "Farewell, Archaic Lord", the Traveler repeated this sentiment, requesting for Missing Person Posters be put up around Liyue Harbor. During the Lantern Rite Festival Event, the Traveler made a wish for their respective sibling, stating "That's my sister's deepest desire." or "I really hope her wish will come true" if you picked Aether as the MC. If you picked Lumine as the MC, she'd say "That's my brother's deepest desire." or "I really hope his wish will come true".

Bough Keeper: Dainsleif
In act I, the Traveler met Dainsleif after fighting the enemies, the Traveler sensed something familiar at a cliff, they then went to the cliff and examined the Dandelion, there was a rewind that was from the beginning of the game, if you picked Aether as the MC, he then says "This dandelion...reminds me of..." or "I...could feel her." and if you then picked Lumine as the MC, she then says "This dandelion...reminds me of..." or "I...could feel him.", after that the Traveler then had to get to the bottom of this but Dainsleif stopped the Traveler, Dainsleif was also now leaving.

In act II, at the end of the act. After the Traveler tries to defeat the Abyss Herald, The Abyss Herald creates a portal but Dainsleif stopped the Abyss Herald and the Traveler's sibling appeared. The Traveler was happy to meet them again although Paimon notices that the Traveler's sibling blocked an attack against the Abyss Herald. The Traveler's sibling continues to tell the Traveler to not team with Dainsleif because he is their enemy. The Traveler's sibling now says to not stop the abyss. The Traveler tries to tell their sibling to come home with them, although the Traveler's sibling refuses. The Traveler was confused, the Traveler's sibling tells the Traveler that they already traveled through this world (Teyvat) once. Once they reach the end of their journey as they did, they will see for there selves the true nature of this world. (Teyvat) The Abyss Herald now created another portal meaning that the Traveler's sibling will now go but the Traveler tried to get them but the Traveler didn't get to the portal in time while Dainsleif was gone because he went in through the portal. Paimon tells the Traveler that show them (Traveler's sibling) what their made of.

Story Teaser - We Will Be Reunited
In the Story teaser we see Lumine's perspective. She acts as the antagonist and we see what had happened to her in the time that she was away from her brother. In the middle of the video, we see her talking to a Hydro Abyss Mage, the Hydro Abyss Mage tells her that someone interfered with the plan to make the Stormterror into a Weapon, Lumine says that the Ameno Archon must have risen to free the Dragon, but the Hydro Mage tells her, that her Brother is the "issue". When Lumine hears this, she has a flashback from the time when she and her brother were separated by the unknown god. Lumine then runs instinctively to a cliff in the Dvalins Ruins, from were she sees her Brother fighting against Hilichurls with Paimon. She then says: "We will be reunited, dear brother. But not here. Not now." She says that they will meet at "this" journeys end, once the dust has settled. When Aether finished fighting, he goes away with Paimon, and we see Lumine sitting inside the Hand of a Ruin guard, and the Ruin guard takes her away into the sunset, and the Teaser ends.

Quote
"May your find your kin at the end of that journey. Well then, let us part ways here for now."

- Dainsleif to Aether/Lumine

"We will meet at this journey's end... Once the dust has settled."

- Lumine to Aether

Fanon
This ship is rather popular as a familyship, due both of them being canonical siblings. Although they haven't had much interaction in the main story, it's clear that the Traveler cares about their other sibling and wants to get their sibling back at any price. This ship is quite popular as finding the other sibling is one of the biggest themes in the story.

Due to both of them having a clear sibling bond, this ship isn't popular as a het ship as incest ships aren't exactly popular in the fandom. However, there are still a minority who ships them as a het ship. It is rumored that MiHoYo loves to make their games sad and have a sad ending, and as such there are a lot of theories that the twin that the player did not choose would die or betray the twin chosen by the player.

This ship currently has about 200+ fanfictions on Ao3, with the majority featuring them being shipped as a family.

Fandom
FAN FICTION

TUMBLR

Trivia

 * Lumine and Aether are 1 out of 4 Genshin Impact Character familyships, with the others being: Klee and Albedo, Kaeya and Diluc (depending on region), Jean and Barbara.
 * In the Voiceline "About Being Sisters", it's confirmed that Lumine and Aether are the exact same age, and that they decide who has to do errands with rock-paper-scissors.