User blog comment:Sithlord Andeddu/Irene's scheme/@comment-88.145.191.141-20160810195135

Here's my hypothetical backstory and motive for Irene. She is Erza's older sister (it seams more likely to me than her being Erza's mom for the following reasons) and she and Erza were living happily in rosemary village until the cultists raided the village killing their parents, along with the other adults, Irene was injured (said injury giving her that scar) and left for dead (she was attacked herself because she either resisted or was mistaken for an adult), when she woke she couldn't discern if Erza was alive or dead and assumed the latter. In the years following Irene becomes a very powerful wizard and develops a cold-hearted and cruel personality due to her traumatic past. Irene later joins Alvarez with the intention of severing all of her ties and leaving her painful past behind her. she wants Erza dead because she jeopardises her current happiness and her loyalty to Zeref (Irene and Erza likely have a similar attitude to loyalty). Irene may want to use fairy heart to power a world reconstruction spell that will remake the world the way she wants it; or more likely, she will be prevented from getting fairy heart, she meets up with and is converted by Erza, fairy heart goes out of control and to prevent Earthland from being destroyed she directs the energy into something like, world reconstruction: happy ending which undoes all the deaths and damage caused by the war (sending everyone home in the process), destroys acno (teleports him into space or something equally lethal) and cures the contradiction curse. If the latter happens finding Irene and the key of Aquarius can be the focus of the next arc.