Calla

Based on Caladrius

Calla takes away human's illnesses and puts them onto themselves, They fly into the sun to burn away the illness

On a cloudy day, in a town plagued by severe illness, all the clouds merged together and a very young Calla appeared. They had no knowledge on survival, however they had an automatic calling towards the ill humans. They discovered they had an ability to heal them by taking the illnesses onto themselves, which then they fly upwards towards the sun to burn it off of themselves.

Through constantly helping and being surrounded by humans, they learn communication and adapt a more "human" lifestyle. Although not treated like a god, Calla wasn't treated equal to a human either; they became a savior-type figure- only appearing around humans when needed. Calla has their own freedom, and although their purpose is to heal humans, they never felt shackled to human-life and thought of humans as equals. (Basically humans see them a blessed figure who's there when they need them the most, and Calla sees humans as equals.)

They hurt themselves for the sake of humans, but due to their younger age as a demigod,  praises still feel great. They're also still able to heal relatively quickly, which is also due to their younger demigod age. Calla is always eager to help again. 

Nix and Calla meet, and although hesitant because of how cordial Calla is to humans, they eventually bond over how similar their lives have been (although at different extremities). Both of them aided humans at their own expense, however still have different perspectives on humans. 

They discover that due to Nix's sun-like qualities, Calla's illnesses are able to be healed by being around Nix. Although they try, but can't "heal" Nix (their outwards appearance), Nix feels healed internally by being able to finally help someone, after a long period of isolation, without it costing their life and another rebirth. After spending years together, listening to Calla's anecdotes, Nix is less wary of humans, and Calla learns to live more for themselves rather than for just humans. 

Both are healed from each other.

DESIGN NOTES:

Their hair and wings fade from white to blue, hands fade from skin color to white with small talon-like fingers, and they have small stars under each eye.