Of course!!! 😀 This is still pretty vague, but I have the basics down!
Mihaela is a “natural” immortal of unclear origins. She doesn’t age, she’ll heal from any wound, and she’s been around for most likely a really long time. Her abilities are just as mysterious, and no one’s sure what she’s really capable of. Mihaela gets bored really easily, though, and pretty much lives for entertaining things. Out of boredom, she turned a human girl, Yuriko, into an immortal like her, mostly just to see what would happen.
Yuriko was just a normal human, but Mihaela’s transformation made her probably not so human anymore. She still ages, but she can heal from anything, and neither of them are really sure what can kill her. Out of a desire to stop Mihaela from hurting more people in her quest for fun things, Yuriko left her home to travel with Mihaela, and the two of them have been all over the place in the two years since Yuriko’s transformation. Yuriko is pretty much Mihaela’s caretaker at this point, in the sense that she’s like 85% of her impulse control, as the meme goes. Mihaela is dangerous, and can and will fuck up people’s lives for the fun of it. Yuriko is pretty much the only thing holding her back these days.
Personality wise, Yuriko is soft and motherly, but very intense and high-energy. Mihaela is a sadistic, selfish person with about half a moral tucked somewhere behind her spleen. However, Mihaela adores Yuriko, and thinks she’s the most fun person to be around. They’re both highly protective of each other, and you can bet that Mihaela has killed for Yuriko before.
How this ties into DL is that Mihaela drags Yuriko into things, cause vampires. Fun, right? Yeah, it’ll totally be fun. She may or may not be up to something highly suspicious, but Mihaela hears about a family of vampires, and sets out to see if they’re any more fun than boring old humans. Yuriko is pulled along, because she really doesn’t trust Mihaela to do anything by herself, and if she lets Mihaela loose, anyone who dies is probably going to be her fault.
From there, it’s an utter disaster of Mihaela fucking things up left and right and Yuriko trying to clean up the pieces. Yuriko I see as having a more motherly relationship with the boys, and Mihaela I might ship with someone. Since she’s way older mentally than the boys, the idea to pair her with one of the adults popped into my head as I was writing this.
Idk though. Mihaela has a mind of her own and will not be stopped.

