User blog comment:Noobinator2k1/Nun's Obscuridad del Santo Andreas/@comment-1265875-20111130184641

I completely finished the game to 100% and rode around for several more hours gameplay taking pictures of locations for the site and never saw the nun myself.

After I posted a question here about whether or not the nun would appear to Jack or if she only shows up for John. No one really knew and I kind of figured, like you, I'd never get the thing.

Then, after I'd let it go, I was running up to the main gate in Escalera and there she was. She stopped me and gave the Obscuridad - better too late than never, I suppose. :D

So the acquisition is very random.