It's her mom, Anna Haias. I think her description of herself is a deliberate callback to how her mom signed her last letter:
--Mom, who loves you most in the world
We know something is strange about her mother because nobody died when the town was attacked and because her mom knew to name her Kubera. And none of the other characters fit -- they either have no reason to care about her, or would care about her too much to let her throw her life away. Her mother, though? We don't know enough about her philosophy to say whether she'd be willing to let Leez throw her life away or not, I think. But it's entirely possible. Look at her in her last appearance there, as the door is closing -- she knows something is going to happen, that this could be the last time she sees her daughter, and she doesn't say anything. Probably it is connected to that.
Additionally, her mom is an established character who was implied to have some sort of connection to Leez (appearing in that later dream); while she's not so established that having her do this out of the blue seems odd. With anyone else, they already have other established "roles", so having them suddenly capable of possessing Leez would be weird.
(Note that my assumption -- based on the 'die a pawn' line -- is that her mother believes that Leez will be happier if she dies here, and is doing this specifically to kill her.)
Edited by Giantess, 06 January 2014 - 01:05 AM.