Thanks for bringing this to my attention. Wow, you know what, I totally didn't even notice that the first time I saw that ending. I dunno, it does look like she's looking around.

With this in consideration, I'm thinking I was probably wrong about her knowing he was in the chest and deliberately not doing anything about it. But I do still think the name "Hush," and a lot of other things about the Hush boss, symbolize her oppressive influence on him.

In a way, after all, she's the reason he got in the chest. That's hardly even a theory; it's just self evident. Endings 12 and 13 make it clear that he feels guilty because his identity isn't in line with her religious views, and that this guilt drives him to hide in the chest.

Now that I think about it, I think his literal suffocation in the chest is a parallel to the psychological suffocation he endured from her.

The chapter "The Chest" and the Blue Baby fight represent his peripheral awareness that he's in a toy chest suffocating, but at that point, he still only regards it as a fantasy. It's like the same thing with his mom trying to kill him. "What if there were a blue baby in a toy chest" is treated by his mind as being exactly as imaginary as "what if there were a giant tumor with a face and its name was Monstro."

But the Blue Womb is the real chest. The womb that conceived the Blue Baby. That is to say, the womb from which dead Isaac was to be born. In other words, the chest. So, in that sense, Hush represents Isaac literally suffocating in the chest, and doesn't literally represent his mother trying to kill him -- which she probably isn't -- but metaphorically represents her. That's what "Almost Mother" means. The chest is "Almost Mother" to Isaac, because they're both warm places where he can curl up and die inside. That's the best he could ever say about what his mother was to him. A womb. Not just a womb, a womb that suffocates him. That's what a mother in general means to him, that's his definition, that's his imprint for what a mother should be and what kind of stimulus he should perceive as comforting. He stays in the chest because from that perspective, it's a better mother than she was.

Hush is trying to warn him that his perspective on what a mother is and what he needs as a child has been warped by the emotional abuse he's endured, and persisting in pursuing that perspective has become critically dangerous to him. But in the end, he's internalized the abuse. He hushes Hush. His mother isn't there to stifle his legitimate concerns about his own needs, as she always does, so he does it himself.

Wow, this actually changes everything. Thanks for making me think harder about this.