[dreamless]

Originally Posted by Ambience Blue

Well...

Spoiler:

At the time of the murder of Mirrielle's parents, Chloe was there too, obviously affiliated with Altena at that point. According to Chloe, watching Kirika kill was the reason why she decided to become an assassin too. So Chloe was part of the program from the start. As for Mirielle, Altena notes that though the seeds were spread on different ground, one had grown rank and unkempt from misattention (referring to Mirielle, who was not taken to the Noir-training-academy and instead lived in normal society.) Due to honoring tradition (with which, Altena is obsessed), I'm guessing that Altena gave Mirielle a chance, but otherwise, didn't consider her a suitable candidate for Noir. Basically, she had the talent, but since her parents refused to give her up to Altena's care, her skills had not matured, nor grown. chloe, thus, the superior killer, hit higher on the list.

Hmm... but

Spoiler:

I remember Altena clearly told that priestess in the last episode that Mirielle is the intended Noir from the start. I think Chloe is included in the program right from the start indeed, but as a final trial for the Noir, not as a Noir. I guess Altena said that Mirielle was "unsuitable" in previous episodes just to manipulate others (Chloe, the priestesses, the other Soldats members, etc. etc.) for her real plan. So that priestess was quite angered and said that Altena tricked them all this time.