Mary in the 1x09 Sneak Preview
Did you poison Aylee? yes or no?
Your friend, Kenna she came to me she found out about Diane’s plot to have Bash legitimized. I saw an opportunity to get rid of them both. I told Diane, about Kenna’s scheming and I gifted her some poison. I suppose I was testing her to see if she’d actually try to poison Kenna before leaving the castle and clearly she tried.
So it was your poison.
Delivered to the wrong girl.