So ... for some unfathomable reason, after Sol does his thing, murdering hundreds for no reason what so ever - he's then going to spare White Chain, again for no reason what so ever.
Ok, cool.
Edit: Actually, I don't want to be too sarcastic here - there are certainly other ways it could go. For one, Allison could barter her key (is it called a key) for White Chain's life. But that would be a poor argument for the point I'm trying to make - that being that Sol is a psycho-fascist bastard without a straight bone in his body.
So just .. keep that in sight: I'm not trying to insult anyone (except, possibly, Sol)