I’ll share mine in full next, if I may!
Meiko, like all her fellow Vocaloids, is a hyper-realistic android. However, she’s not as passionate about singing as many of her companions, which is why she has so few songs and only performs one or two of them at concerts. She prefers to take the roll of backstage manager, making sure things run smoothly and her friends and family get to enjoy their time in the spotlight with as few distractions as possible.
She’s kinda scary - she’s usually very straightforward with her head screwed tight on her shoulders, but she becomes explosive when she’s angry. Still, those closest to her know she doesn’t mean it personally, and they respect and love her far more than they fear her. (Not that “Don’t make me get Meiko involved!” isn’t still a popular threat among them.)
She calls Miku and the twins hers and Kaito’s kids (and, while they view her as a mother in return, they can’t quite bring themselves to think of Kaito as a father. More like a bumbling older brother, really). She dotes on Miku for being the “least problematic child”, but she loves Rin’s fiery energy (if not her destructive tendencies) and is especially protective of Len because of some mental health issues he’s had since his creation. In fact, she’s the first one he goes to when he needs advice or support.
She does love her alcohol, and she’s quite the fun drunk, but there was a period in her life where it was less a fun way of enjoying herself and more of an addictive coping mechanism. Kaito’s the only other person who knows about that time, and as a result, he hates seeing her drink even now, but she insists her current relationship with alcohol is her way of proclaiming her victory over her former demons. Still, he worries she could relapse, so he keeps a close eye on her when she drinks.