Darvali

Darvali is the friendship between Daruk and Revali from the The Legend of Zelda fandom.

Canon
There were no hints at any point in the game that Daruk and Revali know each other before ascending to Champion status. They meet at the Champions inauguration ceremony along with Mipha and Urbosa as they were given blue cloths to show that they are indeed the Champions of Hyrule. After that, Daruk remarks that formal occasions tire him out as Revali becomes interested in Princess Zelda's Sheikah Slate. At Mipha's request, the Champions get together for a photo shoot with one another as Purah instructs them to get into position before snapping the photo, but Daruk pulls everyone together at the last second. Revali is startled by what Daruk did, but it is unknown how he reacted to this after that. Daruk has the idea of giving Link a ceremony to become Zelda's appointed knight who will travel with her. However, during the ceremony, Daruk comments on Zelda's defeated tone in her speech, as Revali tells him off that it was his idea in the first place for suggesting this idea, though he also agrees that the atmosphere of the ceremony is overkill and adds that he is on the same page as Zelda regarding their opinions on Link, before Urbosa hushes them and states that Zelda sees Link as a living reminder of her own failures.

In Revali's journal, Daruk came to visit him and tells him that they must escort Link and Zelda to Mt. Lanayru in the morning and to meet with them at sundown. Revali is bothered by this but remembers Zelda's look, but he opts out of doing it in the morning and instead decides to head out to greet them at sunset instead. They meet with the distraught princess who still did not succeed at getting the results she was seeking. Daruk tells them not to keep them in suspense while Revali already concludes that it did not go well. It wasn't long before Calamity Ganon returns, and Daruk takes control of the situation and tells the Champions to head to their Divine Beasts and tells Link to head to Hyrule Castle, which Revali looks away from Link after hearing this. Unfortunately, Daruk and Revali, alongside Mipha and Urbosa lost their lives after Ganon's blights took control of the Divine Beasts as Link was sent to the Shrine of Resurrection while Zelda seals Calamity Ganon to prevent it from causing further damage.

After Link wakes up, he managed to free the Divine Beasts from the Blight Ganons, allowing them to take aim and open fire at Calamity Ganon.

Age of Calamity
Daruk and Revali are chosen for the task of become the Divine Beast pilots as the Champions, and their relationship is explored further. The two of them have a tendency to get into arguments quite a lot, and it shows in a cutscene where Revali insults Link and questions his competence, which Daruk stands up for Link and tells him it doesn't matter who the leader is, but Revali retorts that he is mistaken and Vah Medoh is the key before talking down to Link again, until Urbosa asks him in a warning voice how long they have to put up with his attitude, before Revali summons Vah Medoh to take out the monsters. During their expedition, Daruk and Revali once again snark at each other until Hestu appears to them and offers to help them. During the gameplay scenarios and challenges when Daruk and Revali are paired as battle partners, they both show great respect towards each other's skills, with Daruk telling him that they really need to spar sometime, and Revali's compliments his strength by stating that no one rampages like he does. In the gameplay after the story is completed, when Daruk heads to Revali's location where he's fighting dark forces, Revali will start telling him that he didn't need his help, but he catches himself mid-sentence and thanks him instead.

Fanon
Darvali is a rareship among fans with only six stories that have them paired as friends, but it does have its fans who like their friendship with one another. Given the significant age gap between the two, with Daruk nearing old age and Revali very heavily implied to be around Link's age, which Urbosa confirms that he and the other Champions (except Daruk) are so young, they prefer to have both Daruk and Revali to just have a platonic relationship and refuse to ever bother having them be anything more than friends in their stories. Given that both of them have opposite personalities as well as their views on Link, it's without a circle of a doubt that they would get into conflicts with each other, and various stories have also put them in conflicts, but there are fans who has Daruk be something of a father figure to Revali and tries to help him lighten up a little and is usually the one being the peacemaker when Revali acts up or gets into arguments with Link. Revali often acts like he does not care for Daruk, but in the end, he does end up making peace with him; it also shows in the game that Daruk and Revali don't get along at first, but by the post-game, their relationship improved to the point where Revali ends up being more cordial and actively tries his best to get used to being more polite and willing to accept help when he needs it, considering that his general proud mannerisms have long been second nature for him.