Okay so I had another epiphany about this scene:
First off, we know that this
is this
and this
is because of this.
Now, if you look closely,
he’s sticking his arm through the upper-left slot. Unfortunately, here
we can’t really see which soul went into which slot, but the upper-left is typically considered the “first” slot, and John is, in a sense, the “first” beta kid. On top of that, someone recently made a discovery about the cover of a bandcamp album from four years ago.
Notice which slot John is in here.
Oh look, it’s the upper-left.
In summary: John got his meta powers by sticking his arm through his own fucking soul.