User blog comment:MDGeistMD02/Which Witch is Which?/@comment-6301921-20131123142036/@comment-6301921-20131123144955

no, there really doesn't have to be a reason. I got Lizzy in cell D24 five times and then in A21 three times.

every time I didn't deal with the scout, I wasn't attacked, but when I did deal with the scout, I was, which is basically the opposite of what happened with you.

Or maybe it's determined at the start of the game, like the floor Timsh is on in KoD.