I mean that church is raising those kids as disposable tools and doing a piss poor job of hiding it from not only the population at large but the kids in the choir. It's no wonder one turned into a demon and the other into a yandere. Though, I think that kid is a demon too.
...but taking into account the ending from "IM"... Yeah, I wouldn't expect too much... Tho I enjoyed reading that manga, the end left me with this... kind of feeling at the end... And she hasn't publish any chapter since last year's October... Or is she on hiatus?
Edit: each volume has almost a year between them... And she published it weekly... So... Does that means that we can have hope about a third volume by Sep-Oct this year?
Honestly they seem to be on roughly the same level to me—murder-happy/psychopathic abandoned kids, whose issues stem from the same abusive treatment, and who have a soft spot for each other.
I can but hope that their relationship is long-lived and broadly mutually therapeutic.