[cyberdemon]

Originally Posted by Kafriel

While the plot is 100% ham-fisted right now, that's the price you pay for making a fast-paced manga. The battles are fast as well, but there are far more fights than there is exposition, leading to an inevitable chapter like this one.

Eileen's past is interesting, but my spidey-senses are tingling, alarming me of a very shallow and BS reason for Eileen to be in the opposite camp. Can she be the friend-proof, moral-destroying villain the series needs? We will find out...almost next year!

Spoiler for Zoro vs Erza:

As much as I loathe Erza's plot armor, Screwattack went out of their way to exclude all of Erza's important fights and how she beat opponents waaaay stronger than herself. Still, although Zoro is weaker than Erza in terms of raw strength, he is a far more accomplished swordsman.

I think there is a simple reason Eileen is with Zeref

Spoiler for speculation:

They are both after Acnologia. I personally think Acnologia being Erza's father would make sense since he was once a Dragon Slayer like Eileen. Love on the battlefield and all that. Unlike Eileen who was saved from her DS curse, Acnologia happily gave up on his humanity. Eileen feels responsible and is seeking to end him even if it means sacrificing everything, like her daughter, to do so. Zeref and his army are just the best option to doing so.