Board Thread:Theories Discussion/@comment-24158566-20141231235231/@comment-6192846-20150101005537

Mariam's backstory is the one I'd most like information on, even more than Germaine or Leonhart. It's mentioned she betrays her unit but it's never really indicated why, let alone why she ended up swearing loyalty to King Arth.

She and Gast seemingly never met before Gast's exile. Their actual meeting (and talking) seems to be during and after his tenure in Beelzenia's service to protect Elluka. Curious how Mariam gets the opportunity to speak with Gast in-length about what happened to his sister and how he feels about it.

We know Gast battles Elluka and that Leonhart defeats him in a duel and spares him his life. It's always possible he was imprisoned and she was charged with interrogating him.

Going back to your question, it's also completely possible Mariam was a part of or at least aware of her mother's collaboration with General Shalgham. She couldn't know have known about Abyss I.R. (Twiright Prank is seemingly the first time she hears the name), but she could at least have been aware of the revenge plot.

It still wouldn't explain her rebellion and defection though. Silver Sparrow Unit wasn't involved in the plan, at least with how Yvette and others put it. It was a convenient occurence that Mariam rebelled, giving Shalgham a legit excuse to park the unit in the mountains and await further orders.

It's also doubtful she was supposed to act as a double agent in Lucifenia as she was already on an important mission. Defecting during that time would make no sense. She could've defected and provided "information" to gain Lucifenia's trust without setting up such a scenario.

And by all accounts, Asmodean was fighting in a defensive war against Lucifenia. It wasn't like this was some "unjust", bloody conquest for territory (that's what Mariam did under Arth's command). It doesn't seem like she'd think her nation was in the wrong for trying to preserve itself from a foreign threat.

At the same time, the fact her mother was seemingly involved with Abyss I.R. does raise eyebrows of any corruption or misdealings in Mariam's relationship with her mother that convinced her to defect.

I'd love to have a (shounen) manga detailing the war from beginning to end with Arth and the Three Heroes. It'd be neat to see them all develop over the years.