Adding on to the vampire, ask,vaggie meets charlie through a ritual carmilla performs to renew a contract of immortality with lucifer, and vaggie learns how to summon charlie specifically. They eventually fall in love and lucifer and carmilla arrange for them to be wed and for their union to act as the new contract
Carmilla has to renew her contract with Lucifer every 10 or 20 years or so. You know, just so Lucifer can make sure things are on the up and up, that Carmilla isn't abusing her powers, and that she's following his instructions to at least use it for some good once in a while. Rescuing young girls who are in danger of falling to the whims of mortal men seems like decent charity, in her opinion.
Lucifer occasionally brings Charlie with him when summoned; she's the heir to Hell, after all. She needs to know how this works, if she's going to follow in his footsteps one day. Except, fuck this, Lucifer's daughter is gorgeous! A real bona fide babe! Vaggie memorizes the spell, then one night when no one is looking, she summons Charlie. Neither of them know what to say; they are struck dumb in love at second sight. Vaggie forms a bond with Charlie almost immediately, and they decide to come up with their own contract together. If Carmilla can summon Lucifer, certainly they can work out an arrangement to keep the magic going, so Vaggie can summon Charlie whenever she wants.
It's not quite as simple as all that. There are some limitations, and Vaggie can only summon Charlie twice a year. Any more than that, she may not be able to summon her anymore at all. Eventually, Lucifer determines that if Vaggie were to marry Charlie, the bond between their realms would be stronger. They agree, and while Vaggie still spends much of her time on Earth, she spends an equal amount of time in Hell.
Also, if Lucifer needs an heir, then so does Charlie eventually! He doesn't know how that's going to work, but he can make it happen, if they want it to! He won't be demanding about it, but if Charlie and Vaggie kinda decided they want to have a kid out of their union, who is he to complain?! He'd be killing two birds with one stone (and be very happy about it, too!).









