Though both are friends, Diona and Klee have never canonically interacted in the current story.
Both, Klee and Diona have a voiceline about each other:
In Klee's voiceline about Diona, she tells the Traveler that Diona is the best and that she likes listening to Diona. She further says that last time Diona said that she will destroy the wine industry in this city, if it's the last thing she will do. Klee then then offered to help Diona to destroy the wine industry with her bombs. However, Klee admits that she doesn't even know what a wine industry is and asks herself if it is a big monster.
In Diona's voiceline about Klee, she tells the Traveler that every time Klee wants to play with her, she takes her far away from the tavern, because alcohol and explosions are a dangerous combination. She further says, that she does wants to destroy the wine industry of Mondstadt, but that she doesn't wants to do it in "that" sense.
Klee and Diona are both from Mondstadt, meaning that. They're also friends. Both, Klee and Diona are almost the same height and are identify as young girls due to their appearances. Their appearances are being complimented as "cute" and "adorable" appearances, this also goes the same to Qiqi, Yaoyao, and Sayu. The both also have visions, being Klee's vision is Pyro and Diona is Cyro, when you ascend Klee, you get Pyro Damage Bonus and for Diona, you get Cyro Damage Bonus when you ascend her. Klee and Diona also both have some similarties in how they are dresses, both wear a short trouser for example.
- “Diona is the best! I like listening to her, last time I heard her say, "I'm gonna destroy the wine industry in this city if it's the last thing I do!" And I'm gonna help her using my bombs! ...I don't know what a wine industry is though. Is it a monster?”
- — Klee's Voiceline about Diona
- “Every time Klee wants to play with me, I take her somewhere far from the tavern. Alcohol and explosives... yeah, that's a dangerous combination! I mean, do I want to destroy the wine industry of Mondstadt? Yes, but not in that sense!”
- — Diona's Voiceline about Klee
Kleeona is widely disliked as femslash ship because of Klee and Diona's child-like looking designs. While the ship isn't popular as femslash ship, its quite popular as friendship, because of Klee and Diona's amusing friendships that is mostly explored in Klee and Diona's voicelines about each other. The ship has a good amount of fan arts, often Qiqi is also pictured on artworks featuring Diona and Klee. Mostly because of the popularity of the famous Genshin Impact poly ships: "Chibi Squad". There are currently 6 stories on AO3 for the two as gen ship, and 2 as romantic ship.
There is a small part within the Genshin Impact fandom, that ships the two as femslash ship. Altough, that is seen as highly controversial within the other part of the fandom. Many people have theorized that Klee and Diona are children, mostly because of their appearances. Despite this Klee and Diona's ages were never confirmed, leaving a part of the fandom arguring that the both of them aren't children, and might be even about 14 years old. Some people also theorize that Diona might be even an adult because of her serious personality.
- Both can be seen together with Qiqi on the official childrens day art that miHoYo posted to celebrate the official childrens day.
- Chibi Squad refers to the ship between Qiqi, Diona and Klee