>>536654741
Implied by Desna's interlude in the Drama CD that Olga unintentionally put Eden on the bad path. It's played off as a joke, but the stars were aligned with Eden up until their experience with Olga gave them the final push towards exterminating all nonadepts, and gave Zonda the plan to merge herself with Lumen.

>>534753089
It's the hair and final battle, though if you ask me, she's got a bit of Ciel in her as well, more so Alouette.