In terms of AH:Coven. Hubby has done this before. His comment about going last Halloween as a "monster" makes it pretty clear that this is at minimum a Halloween ritual for him. Perhaps it is part of a spell Fiona cast for him, which would explain why she does not like him being with her daughter, and why she won't explain why she does not like him being with her daughter. Not that Fiona does not seem to prefer lies to truth in almost every circumstance.

Also, if Fiona is not dumb as a post, she is careless to the point that amounts to the same thing.

For example: she digs up Madame, without even considering the possibility that this might have something to do with Laveau. She definitely knows about the treaty, and how staying off one another's territory is the main agreement. But having taken something of Laveau's, she walks onto Laveau's personal property without notice, is rude as shit to Laveau's people, and even ruder to Laveau with the "hammer and nails" remark. How else is Laveau going to take this but as a declaration of war? Yet Fiona seems to have done all this just as a way of trying to gain immortality with no intent of declaring war. She just assume Laveau was going to bow down before her, and sell her immortality - at a very high price no doubt. She is too arrogant for elementary diplomacy: "Hey, I unintentionally picked up something of yours, without realizing it belonged to you. Should I return it to your place? Or would you prefer to send someone or something to mine?" Once that is cleared up she could arrange a meeting where Laveau might be willing to do business.

Also, she didn't even check medical records before murdering Madison? She may have grown old, but she really managed to avoid growing up.

His comment about going last Halloween as a "monster" makes it pretty clear that this is at minimum a Halloween ritual for him.

I think that's sort of a giant leap to take. We've seen him do this once, and we don't even know why he does it.

I'm betting it was not the first time. Yeah my guess as to how often and why is pure speculation - though I think this kind of speculation is part of the fun. But he has done this before, whatever the reason turns out to be.

I don't know that it's this, exactly. I kind of expect not. But the remark about being a monster last year was extremely pointed. Dude's got something dark going on.

How long have they been married? Do we know?

Is he a warlock?

The monster comment was definitely a clue to something. Not sure he practices witchcraft, though -- so far even the most "monstrous" men in this series don't seem to have their own mojo.

I think it's unlikely that someone who hasn't killed before would take a handgun with silencer to a first-time internet hookup and blow her away without so much as flinching.

Right, but that's also why I don't think he's a *serial* killer in the usual sense. He's more like a hitman. I don't think (yet) there's any reason to believe this is a ritual he carries out every Halloween.

Maybe he's doing something really weird, like harvesting the girl's eggs or something.

In this world, I'll bet the killing has to do with some sort of magic, even if he is not casting the spells himself. Maybe he'll turn out just to be a hitman, but I'm guessing spell connected murder. Maybe ingredients for a spell? And I'll bet there is a reason he has killed two Halloweens in a row. There is really strong reason to think he killed last Halloween. Not 100%, but at least 50/50.