"Listen, can you maybe explain what you're talking about as though you're talking to somebody who actually hasn't ever heard of leafy fairies with crazy hypnosis powers before?"
"I have your name. I can tell you what to do and what not to do and there are not alternative options, not if I mean it. I am a nicer than average fairy, but this very niceness is incompatible with you going around eating people now that I can stop you. He's," she indicates Tea, "going around without any particularly intrusive orders on at all, but I didn't catch him about to murder someone, so if you want to get on a blacklist arrangement of orders instead of a whitelist that's going to be a process and if you want to go all the way to trusted to behave without orders at all that is going to be yet more of a process."
"...Okay but what, like, is the process, what do I do to prove I'm a good little vampire," he says.
"I don't know, I wasn't expecting to acquire another vampire tonight, but here we are. Probably the shortest version would be commanding the truth out of you and then having some extended list of questions about under what if any circumstances you might revert to your old habits, but we're expected elsewhere soon."
"Okay, now I'm kind of confused about how hard you expect not eating people to be."
"And so you expect us to believe you will consign yourself to an eternity of the less fun option because...?"
"Turns out most of the fun of hunting is not actually in the eating of people? Like, I'm not one of those hardcore end-of-the-world types, I pretty much just want to drink blood and kiss cute boys. Separating the two isn't going that far out of my way."
"Then you will not have any trouble resolving a future interrogation to my satisfaction. But for the time being I don't have one mapped out, so you may either stand here immobile until we come back or you may accompany us."
"Hi," she says.
"You must be Promise, and that must be Mr. Holmes, and...?" She looks from Promise to Tea to Zeke and raises her eyebrows.
"Do you want to pick a nickname?" Promise asks Zeke. "It won't do any good here but it will mean I don't have to make something up if I must introduce you to other fairies for some reason."
"You can call me Castle," says the woman, getting up. "I'm the Slayer's aunt. For fairy purposes she's nicknamed herself Royal."
"And this is temporarily Vampire Two, who will think of something eventually," says Promise.
"I'm sure Royal will be fascinated to hear how you ended up collecting him."
"Accurate prediction," says Royal, emerging from the library. "Do you have a nickname to complete the set, Holmes?"
"I admit to some fondness for 'Tea', which Promise has been using," he says.