I figured that Cyan was a good boy and the mom was the culprit but I didn't think she'd drug her own son. She must really hate this country with the exception being her late husband (presumably).
Honestly, I don't hate the chef. I cook myself and I learn most of my recipes from watching people cook so it's not that weird. Other than him claiming it's his creation and refusing to listen to other people's input, it's pretty standard cook behaviour.
I have a feeling that the noble house once captured and imprisoned a wolf that later cursed them. Theo just so happened to find the prison on the estate but forgot about it.
So, did people really forget about the whole dragon eater guild? The moment he said he was summoned to kill Selene and that he's enemies with FT, I immediately knew he was from the other guild.
Keep in mind the three groups: Fairy Tail, Dragon Eaters, and finally Dragon Gods.