Anna’s bizarre behavior has been all over the map during her haunting-slash-incubation period. Apart from her physical deterioration — see below for more of that — she’s losing heavy chunks of time and blacking out for long stretches, only to come to and realize she’s agreed to things she can’t remember what she’s said or agreed to. She also keeps seeing Ivy (Cara Delevingne), the nurse who attended her apparent miscarriage, wherever she goes, as well as an Adelaide lookalike. And then there was that unfortunate incident where she ate the corpse of a maggot-encrusted, very dead raccoon — an incident that is never brought up again after it happens.
The ultimate question is — how much of this behavior is controlled by Anna, and how much of it is being caused by her demonic spawn? After all, we’re talking possible unsavory magical deals — there’s no way the baby itself doesn’t have some power over its human host. But the narrative hasn’t confirmed these things either way, so we’re going to mark this one as an open question.
Since it’s quite possible that Anna’s actual human child was aborted by Ivy and replaced by a demon spawn due to her ambitious wishes, perhaps her behavior may have involved some drugging from outside sources (see below). But if it ends up being the influence of her tiny dark passenger, don’t be surprised.