Isabela Auclair (Lucifer's Angel)

Boy, oh, boy do I love song references
10 points to House of Lamentation if you guess it right lol

Anyway
remember when I said Isabela was a regular human?
I fukkin played myself
baby sister of Diavolo who was in love with Lucifer before the Celestial War
She was on her last breath after being attacked by their older brother Azrael
Diavolo used his magic to have her reborn as a human and so because that's his precious baby sister he didn't like the idea of her dying so every time her life comes to an end, she's reborn
Had encounters with Lucifer before all that and they fell in love
Never told him she was princess of Devildom

After choosing Lucina and Solomon for the exchange program, Diavolo insists on another human, as Solomon is no average human. Lucifer grew frustrated going through files and not finding another human who would fit well in Devildom. He walks from his desk to the window. A breeze flows in, blowing the papers on his desk around. He exhales a breath of defeat. He bends down to pick up a file that landed at his feet. When he looks at it, he's overcome with a wave of grief. "She looks just like...even now that face still haunts me..." He looks at the name and is taken aback. "Isabela...she even has the same name as her..."  And he decides to bring her to devildom, if anything because she looks like the only woman he's ever truly loved. And when she does arrive and is being briefed by him and Diavolo, he feels this strong pull towards her that he cant quite figure out. He simply assumes his emotions are confused, thinking it's the same girl he fell for in his celestial days.