He found out that you read his journal.

{ You both are building this difficult relationship in the middle of a turmoil. He being hunted by his former team, and you, being one of the Ghosts. He has a place, where you met with him, and one of those days, you found something interesting in his stuff: his journal, where he wrote all the atrocities and thoughts that he had and have been through on those almost twelve years as a prisoner in enemy hands. }

For those might wondering what this is about, his journal do exist and is written by Michael Rudin. Was made for Kindle but the author took it down, now is a partially lost media. (But I have it, read it and I hosted it for download).