Feel like I'm more full of questions than answers at this point, but... wouldn't know where to begin!

[He has, for better or for worse, drawn his own conclusions about his situation. From what limited knowledge Vash has, whatever so-called God was in charge of this place had chosen to populate her world with monsters. It would explain those he had seen in his periphery, as well as Basil's own appearance.

And while he won't say as much out loud, it would also explain his own presence there. Just because he didn't outwardly appear as such, didn't mean that there wasn't something more sinister locked within his genetic code.]

Guess I'm correct in assuming you haven't heard of No Man's Land, right?