#rito!dal

During the day Dal has duties to attend to (looking after Zelda, training, etc), so he doesn't even bother to pull the mask out and look at it during the day.

Your first guess hit the nail right on the head, my dear anon! owo)b

I always sorted it in my head based on which era the AU takes place in:

The Rito Mask AU takes place in the Pre-Calamity era, where Dalex is a Hylian that becomes the Legendary Hero instead of Link. Once Dal gets the Rito Mask from the Happy Mask Salesman, humor and angst ensues.

The Rito!Dal AU takes place in the Post-Calamity era, where Dalex is born (or rather, hatched) as a Rito and is the descendant of Revali's best friend. After Vah Medoh reappears and Harth gets injured, Dalex volunteers to go with Teba to take the robo bird down. He comes back with a certain blue-feathered Champion that's in need of immediate medical attention.

Yes. There are three ways the mask wouldn't work on him if he put it on:

It’s daytime.

It’s the night of a new moon.

This started out as practice drawing Dal's beak, since I was worried I was getting rusty

Then I just kept going

God I really, REALLY want Dal to be able to play the guitar