Ok I’m only on the edge of the fandom because I’ve not followed anyone for it specifically, but I’ve not seen this theory cross my dash. Maybe it’s a known thing I don’t know. It slapped me in the face the moment I watched the episode but (again) because I’m only on the periphery I didn’t think about posting it.

THE THEORY

Agatha killed witches.

The day she did not kill witches because Nicky wrecked the play and “mama we can kill witches tomorrow” was the day Rio came and got him.

What if Agatha was killing witches to buy more time? – “I can offer only time”. Nicky was what nine years old? Why that age? Why not four? Or seven? Or sixteen? Rio is death and deaths payment is – death. Agatha killed and killed to pay death off and keep Nicky.

So when she woke up and Nicky was gone, Agatha blames herself because if she’d killed the witch as intended, she’d have bought another day.

Just a thought 🙂