Haziel's wings are black speckled with white where Anaphiel's are red and a dusky purple where Anaphiel's are gold, with similar fading in between them. He's not as good at pretending to be human as Anaphiel is--his face is often expressionless and his voice is often toneless (his human voice, anyway; when he speaks Angelic he sounds as lively as anyone) and his body language is stiff, but he complies when reasonable requests are posed and he really does know his math.
Mehitabel does not require warmth from Haziel. She just needs to know how much divine energy she should expect various tasks to take under what conditions and what her recharge rate will be given various assumptions, and similar things about God and angels and anything else running on comparable battery systems.
Relevantly: Learning science will help a lot. The more she knows about how any given task works, the more of her own detail work she can do and the less energy it takes.
Oh, well, then. Mehitabel increases the science/other ratio.
Interestingly, demons don't work the same way as Mehitabel and God and angels, but they work similarly in some ways. He will enumerate the technical details of the similarities and differences and why the similarities are important if she likes. One difference is how they recharge. The kinds of demons that do torture recharge from pain, succubi and incubi recharge from sex, wrath demons recharge from anger, etcetera.
Oh, dear. That makes it less likely that she will be able to reform the demons, doesn't it. At least the ones whose recharge mechanisms are particularly reform-incompatible.
If she is particularly determined, the source of the pain is immaterial. And masochists do exist.
If she is intending to do significant work with demons-in-general he recommends finding an adviser who is one of the not-actively-terrible kinds of demon.
That sounds like a plan! Where might such a commodity be found?
"I'll find you one. It'll take longer than finding a magic instructor, but I can do it," she assures.
Now that Haziel knows that demons are an area of interest, he has some more technical detail on those, too.
How fascinating! (Demons are very interesting because if Mehitabel turns out not to be able to solve the technical problem of awful people going to Hell she may still be able to solve the social problem of Hell being full of demons making it particularly unpleasant. There aren't even that many demons.)
That is mostly not an option that has been considered before, largely because of the risks inherent in the prospect of getting the really nasty kinds of demons out of Hell to talk to.
Well, maybe the nicer demons can be emissaries to them within Hell instead.
Probably she wants to get large numbers of non-terrible demons on her side before she goes after the really nasty ones, though, since those are much more powerful.
Yes, that seems reasonable. Even when the strategy is more "missionary work" than "holy war", it is probably not wise to bet on particularly evil demons not trying to shift the equilibrium.
Getting large numbers of non-terrible demons on her side is probably something she can do. Mostly they care about the things that give them power (succubi and incubi care about sex, wrath demons care about being around angry people, sloth demons...probably hang around sleeping people creepily? What do sloth demons even do) and Mehitabel seems likely to be competent at figuring out how to get them more of it more efficiently and ethically.
It is weird that there are things the angels do not know like that.
Well, God probably knows, and for every given thing there is probably an angel who knows it, but not every angel knows every thing. If they did, Anaphiel could have just taught her battery math herself and Haziel wouldn't be here.