so  made a name for them and I wanna make their backstory

so here you go-

Luna(pink hair) was born with a weird birthmark around her mouth, in which in her village, she is the descandent of the warrior who made the village years ago

So Luna was taken away from her parents and was raised to be a noblewoman. While Brianna in the other hand was treated poorly because of her eyes. Luna and Brianna are childhood friends, because Brianna is Luna's maid.

It went on like that. Luna is 17 and Brianna is 15.

After an attack at the village, Luna and Brianna accidently went to the human world and were targets for the humans who are amazed by their 'unique features'

Then Caster/Loki came and Brianna kidnapped him, and Caster/Loki didnt came back home.

At first, they were going to use him to disguise themselves. But after learning he was not human, they just decided to spare him. Loki/Caster decided to tag along with them since he's bored of his current life.

Also Luna and Brianna have a sibling-dynamic relationship, since Brianna sees Luna as family.