Breath of the Wild
Revali once lived in Rito Village and was considered one of the best warriors of his race. Before Calamity Ganon's return, he was chosen by King Rhoam and Princess Zelda to become the Rito Champion and pilot of the Divine Beast Vah Medoh.
Revali was killed when Windblight Ganon took over Divine Beast Vah Medoh. One hundred years later, Link returned to free the Divine Beast. Revali's spirit acknowledges him upon entering, and shows Link where the map of Medoh can be found. After opening all of the terminals and activating the main control unit, Windblight Ganon appears and Revali advises Link to use caution.
After the battle is over, Revali appears before Link as a spirit and thanks him for defeating the monster and freeing both him and Medoh. He grants Link Revali's Gale, which allows the hero to create a column of wind which Link can utilize to fly into the air. Revali then takes Medoh to the highest point of Rito Village and takes aim at Hyrule Castle. Upon Link's return to fight Ganon, Revali uses Vah Medoh's power to weaken the beast.
After Calamity Ganon's defeat, Revali's spirit is shown with the other Champions and King Rhoam high above Hyrule Castle. After momentarily watching Link and Zelda depart, his spirit disappears along with the King and remaining Champions.
Revali had an unwilling relationship with Link as is continuously shown in Link's memories. After becoming the Rito Champion, Revali was upset that as the pride of the Rito race, he became nothing more than the assistant to the Princess' Champion. Before Calamity Ganon's return, Revali never believed in Link's ability to become the Hero of Hyrule, and looked down on him as a constant disappointment. Once Link defeated Windblight Ganon, the Rito finally acknowledged Link was a hero who could defeat Ganon, and stood behind him when Link went to face the beast in Hyrule Castle.
Age of Calamity
"A gifted archer who has mastered an aerial move previously thought impossible. While boastful, he has the skills to back up his claims. Now, he is entrusted with piloting Divine Beast Vha Medoh"