Well, I was thinking. If Harry were to take the Deal Bianca offered him, there's no Summer Knight. Aurora succeeds in unbalancing winter and summer. There's no paranet, because Elaine never leaves Summer. Harry doesn't become Winter Knight and Maeve manages to call down Outsiders unto demonreach. There's a very good chance that Harry accepts Lashiels coin, or young Harry accepts it, and the carpenter family is killed from within. Meaning that there's no Molly or Michael. Harry accepting Bianca's desk would have been a very bad thing.