This one is a literal journal entry and by none other than Morgan. Yes, he's been dead since the second-to-last novel but since there are major spoilers for at least the previous volume, I didn't want to read it until now (plus, GR says it is supposed to be read now).
Shortly before Morgan died, he wrote this, granting whoever gets to read it insight into A LOT of things related to Harry.
It was interesting to learn of Morgan's true connection to Harry but if anything, it made me hate him for his behavior even more! The end rarely ever justifies the means.